Every single thing you just said is made completely and utterly irrelevant because of the cloud. If you don't have a mac, then you can easily use Dropbox, or a million other free cloud services.
Emailing 20 documents...? I don't know why you keep acting as if this needs a file manager, or as if a file manager would somehow make this ANY easier. Because it wouldn't. Apple could easily just give you the ability to select a few documents in Pages and hit the share button. That would be a lot easier than some sort of file manager.
Copying a lot of photos to the iPad? This is even easier, on a mac just add them in to Photostream. Done. How, exactly, would a file manager on the ipad make this any easier? I can't imagine having to use iTunes to copy photos to an ipad. There are ten thousand ways to do this, including many ways offered by Apple themselves, and iTunes would be my very last choice.
You say you "want an easy way to share documents between programs" on the ipad? Apple said 2 months ago that with iOS 8 they will be coming out with an extremely simple and powerful Extensibility framework that will vastly improve inter-app communications. It will do things like allow third party apps to add their own filters directly in to the Camera app. Extensibility, in my opinion, is a FAR easier and far more elegant solution to this problem, not some 1990's style file manager.
You're right that Apple could just as easily let us share more than one document in Pages.
That solves the Pages issue... now what about all the other apps that only let us send one file? At the moment the
app has to allow us to send multiple files, but we are proposing that the
OS allows us to send multiple files. I.e. the app doesn't even have to support it - any app that saves files is instantly supported!
Why on earth would anyone ever want this...? Perhaps I am too young, but I never did like the old folder-directory style of doing things on computers. It was very inelegant. For example, you click the "upload picture" button on a website, and it requires you to navigate and sift through your entire hard drive trying to find the folder that you dropped the photo in to. THAT is how iOS is superior, because in iOS it literally will immediately let you pick a photo from your camera roll.
A filesystem is powerful, and it's how software (even on mobile devices) views the computer, but in terms of actually doing things on a mobile device, a full fledged file system would be impractical for 99% of the users out there who just want to check Facebook and play Candy Crush. You can't blame Apple for valuing 99% of their customers requests over the 1% who want some ancient filesystem UI.
So you click upload picture... a box pops up,
"Upload picture from...
[Camera roll] [Filesystem]"
Tap your option.
Best of both worlds.
Let me ask you this. Do you know how many thousands of people delete a text message every day and then call Apple asking why it "went away"? Or how many thousands turn on some Accessibility feature and then call in to ask how to turn it off? Can you even comprehend the damage and headaches these people would cause if they had access to the entire iOS filesystem? These are the people who don't own computers because they don't know how they work.
File systems, folders, directories, etc. genuinely confuse these people. While someone like you and me obviously know how file systems work and love computers, the "masses" don't, and they much prefer the simplicity of a mobile device to the file system of a computer. These people make up a huge number of Apple's mobile customers. You can't blame them for wanting to try and appease them and the power users with a kind of middle road approach. I think that Apple's whole Extensibility framework for inter-app communication and file sharing is gonna fix all of these problems that both of you keep bringing up. There are much better ways to solve these problems than simply throwing in a filesystem.
Nah extensibility won't cut it.
What if I want to: -
1. Type a letter to a client (Pages)
2. And attach to the letter an invoice (Numbers)
My letter is saved in Pages and my invoice is saved in Numbers.
It would make so much more sense if I could save both documents in a folder called "Client_name"
Extensibility won't solve this, not in the slightest.
File management is something Android does right and has over iOS, IMO.
By default there is no file manager installed on most phones (or wasn't last time I used Android a couple of years ago) and the file system doesn't have to be exposed to the user. For those that want it, however, you can install a file browser app and have full access to the file system.