epic tides of text commence!
If your camera has an interface this easy, then you are lucky....
But the thing is, my D80 was I believe at the time the second lowest DSLR you could buy from Nikon. Extra buttons was pretty much exactly why I bought the D80 in the first place. Nowadays it's modern descendent is the D7000, the third lowest Nikon DSLR you can buy. Get in the game at that level, and IMHO a lot of these interface problems simply disappear because you have hardware buttons. Even the lower end D5100 and D3100 have relatively intuitive "info" screens where all basic adjustments can be pretty easily configured. The D5100 and D3100 each also have a programmable function button, which can be used to set either ISO or WB (among other things). You can't get both, but you can get at least one. And I'd argue shooting in RAW you largely don't need a WB control, so set it to ISO and you're set. All these cameras have a hardware exposure compensation button.
I don't shoot Canon but again, a similar story can probably be told. A quick look at dpreview and I see that even the lowly 1100D (I'm guessing D5100 equivalent?) has a pretty full array of hardware buttons as I describe. It actually seems like the low end Canons are better in this regard to the low end Nikons.
Essentially, I guess I'm saying don't even bother with the bottom barrel model, because functionally it is no better than a P&S, and as such you lose a major reason to even use a DSLR in the first place. But people buy D3100s and Rebel Tis in droves because they're cheap. People buy DSLRs thinking (or being told my marketing) that they need one, but don't really know why. And because they don't really know why, they just get the cheapest one possible and assume "hey, it's a DSLR right? My pictures will be great!!1!!1"
Here then it seems, is a case of "you get what you pay for". Yes, D7000s and 1100Ds are a little more expensive, but they are certainly not out of reach for many. Especially considering how many of these very same people run around toting iPhones and iPads. It's not like you have to buy in to a $3000+ camera body to get this level of "usability". Anything even slightly above the absolute cheapest, most bottom line DSLR pretty much negates many of these stated interface issues.
To answer your question of what benefit an iOSified interface would bring.... App Store. An Apple camera could come with a basic - but very good interface - but would allow the user to buy interfaces from the App Store. That way you could have an interface that looked and felt like a Nikon, or a Canon, or an Angry Bird. Instead of spending an evening thumbing through your manual and customizing menus and buttons, you'd spend $.99 and download an interface - spend 15 minutes customizing that interface - and then save the previous bought/customized interface for later use.
I still don't see the benefit. First you say that Apple has the talent to revolutionize camera interfaces, and now you suggest that we don't even use Apple's interface and instead use the $0.99 app that some random basement programmer comes up with, who probably has zero experience in human factors or ergonomic design? And you state that I can even buy an app that makes my camera operate like a Nikon DSLR? Great! So I can buy a camera from Apple, and pay more money to buy an app that makes it act like the Nikon DSLR I already own! Wait, why were we doing this again?
Maybe I'm in the minority here but honestly the Apple "app" ecosystem really does nothing for me. I have an ipod touch, and it has maybe 5 3rd party apps I actually downloaded and use. The overwhelming majority of them are either poorly written/executed, or do not do things I really want or need that I couldn't already do with the built-in apps made by Apple. And Apple fails just as often in their own interface. Why does the iPad have no native stocks app? No native weather app? Now I have to go pay more money just to get that basic functionality I had on my ipod touch onto my iPad? Or be saddled with some ad-ridden, limited, freeware version? The app market really seems designed to sucker money out of people, but slowly, $1 at a time, so they don't notice the bleeding. Yes, there are some very worthwhile and useful apps I'm sure, but is this really beneficial to the question at hand (DSLR interfaces)?
And as far as customization of the interface goes, I stated in my previous post I can do that already. I can hide any/all menu items that I don't need on a regular basis, so my menu system is very compact and simple (the menus on my D80 are cut down such that I barely even have to scroll past one screen of menu items). How many DSLR owners are even aware this exists on their camera? Probably very few, and IMHO it's their fault for not reading the manual that came with their camera. And here the proposed solution is to buy another camera that lets me pay yet more money to troll around looking for the right app that I want/need to use as my camera interface?
Is it really too much to ask to sit down and spend 1 hour going through the DSLR manual and setting up the camera just the way you want it? That new, very expensive camera you probably
really wanted because you just blew several hundred to several thousand on it? You are so impatient that you would rather just pay yet more money to people to have it set up the way they think you want it? Is our society so transient and lazy that we are reduced to this? Pay a dollar to fulfill an immediate need for satisfaction? I certainly do not. I don't know how long it took me to read the manual to my D80, but I do know that it couldn't have been that long (an hour or two at most) and I enjoyed it very much. I read through it once, carefully, and have basically never looked at it again in the 5 years since I got my D80. I think I used it again about a year ago when I got my external flash, so I could review the flash commander settings that I had never used previously. No, the manual is not shakespeare, but it certainly was plenty clear in its presentation of the material. Maybe people just need to learn to read technical documentation.
My thinking in that thread is that Apple could put an array of smaller lenses/sensors on the front of the camera and use SW put the disparate images together into a single image.
A big drawback to this specific example is that you lose thin depth of field, which is one of the primary reasons for using large sensor formats. Anyway, again- optical physics is not really that complicated once you get down to it. The advances of the past 100 years have come in our ability to make the lenses "properly". Antireflective coatings, aspherical surfaces, low dispersion glass, it's all about manufacturing. 100 years ago people had already figured out the mathematics and theory of how to design very high end, optically superior lenses, they just lacked the materials technology to make them.
Here is a great article written by Roger Cicala, the owner of LensRentals that illustrates in reality how relatively simple (conceptually, at least) even modern SLR lenses are. Another good read is the article on lens coatings that is linked in the article. Again, the fundamentals behind this are all pretty straightforward concepts. It's 100 year old technology because we more or less figured it all out 100 years ago.
Apple certainly isn't going to be breaking new ground in this area. Any real advance they make is probably because they bought some startup or someone else invented it and they merely capitalized on the concept.
-Why should shutter speeds change by 1/3 of a stop in one mode, but 1/2 stops in another mode (same for apertures)?
-Why should the ISO change values if I change modes?
-Same thing for WB?
(I've seen this where the camera resets the WB or ISO to last used value for the previous use of that mode -instead of assuming that you are changing modes while photographing a subjet)
-Why should the settings menu for basics like ISO/WB/etc change location depending on what mode you are using?
-Why are there "basic settings" and "menus" and "custom settings" and "advanced menus"?
1) I don't have this problem. 1/3 or 1/2 stop increments is a setting I set up in the menus the day I got my camera and never looked at again. The setting is preserved no matter what mode I operate in. Does it really not work like this on everyone else's camera?
2) Because when you go into the auto modes, you sometimes trigger auto ISO. This is usually explained in (gasp) the manual
3) See above. Another common failing here is a lack of workflow discipline. You should get in the habit of checking X, Y, Z items every time you shoot. Once you ingrain this concept into your head, it only takes a second to check, and becomes second nature. Or you should get in the habit of resetting your camera functions to a standard state when you are done. Every time. It's like making sure your gun is unloaded and safety on when putting it away. Being lazy on things like this often leads to the "I don't know why it's doing this" situation.
4) Not sure, but if you buy something even slightly above the lowest end DSLR, you likely don't have this problem because you get a dedicated button for that
5) Probably to segregate the functions by category. Basic menu is for things you might change often or might change as a beginner (WB, ISO, etc). Advanced menu might be for things only advanced users would know/care about (for example mirror lockup or built-in flash commander settings). Custom settings is probably for changing the way your camera operates, and not adjustments to shooting settings (like how big of an area to use for the center-weighted meter, sleep timer, 1/3 or 1/2 stop adjustment increments, etc). More like "set it and forget it" types of options.
I will agree maybe some menu readjustment would help, but again you just need to understand why it is divided up this way. And it's usually all explained in the manual. Read it. One good read-through is usually enough. If that's not good enough, there are plenty of hint books, cheat sheet cards, etc. people would be glad to sell you. Don't forget- you seem totally willing to pay money for apps that would ultimately do the same thing!
Most DSLRs seem to include the basic functions amongst all the other advanced functions. There is a fundamental difference, to my mind, to putting the advanced functions in the background vs making them look the same as the basic functions.
"Most DSLRs" again seems to boil down to the one or two lowest end models each manufacturer offers. Now by numbers, they may comprise a significant fraction of the DSLRs in the wild, but if you go by model, "Most DSLRs" have dedicated hardware buttons for practically everything you need. 7 of the 10 cameras advertised on NikonUSA's website have hardware buttons equal or greater than my D80.
And here I thought it was because it makes DSLRs appeal to young male consumers with disposable income... what was I thinking, eh?
I don't doubt it, but you think Apple would market their DSLR any different?
An Apple camera is going to stream photos to the web for you (vacation blog, updated while on vacation). It's going to synch seamless with iPhoto or Aperture - while you are shooting - so you can buy more products like books and cards and calendars from Apple. It's going to synch with all of the social media sites and photo-sharing sites. And it'll push photos out to your Apple TV so you can bore your friends with a slide show of your trip to Disney Land. Just like our my parents did.
IMHO what's really holding things back ere is the wireless telecom industry. Apple can't do much more about it than Nikon or Canon. They all know this would be a great feature, but it's impossible to pull off as a business. No camera will ever come with a cell connection without being tagged with hefty monthly bills from the telecoms, not unless (surprise) it's a cell phone camera. Even if you went the modular route and made an iPhone app that made your cell phone act as a mobile hotspot, and then used an eye-fi SD card or similar, data charges simply make this an untenable prospect.
I'll agree that one thing Nikon and Canon lack is the willingness to embrace 3rd party solutions like flickr or twitter integration, but truthfully Apple is pretty restrictive in this regard too. How much money you want to bet that an Apple DSLR won't automatically upload into Adobe Lightroom, my photo editing app of choice? I'd be just as shackled.
Don't get me wrong, I am not out to refute everything you say, it's fun to debate these things with you

. I get what you're saying, I just don't think Apple could really bring to the table what I really think is missing in the DSLR market. And that is, a user willingness to learn and utilize a tool. A lot of users buy DSLRs as fancy toys, status symbols; not as photographic tools. It's no surprise then when they find it's too complicated or requires too much effort to properly handle.
It's really strange how it works that way too. Once I went through old photo albums that my parents had. The photos in them were taken with a Canon AE-1 SLR (which we still have, BTW). The pictures were great. Shallow DOF, good composition, I was amazed! What do they use now? A simple P&S camera. They don't care about DOF, don't care about composition (as much), it seems like the photos they take now are (artistically) worse than what they were taking 30 years ago. What happened? Maybe it's because back then, in order to use an SLR you really had to learn some of the fundamentals because DSLRs were fairly manual affairs. If you wanted to shoot your own pictures, you HAD to learn about shutter speed, ISO, etc., and it made for some great pics. Nowadays with automatic everything, people just don't have the desire to learn, and just want the device to do it all for them. And as we repeat so often here, it's not about the camera it's about the person holding it.