The optical drive being a 'con' sounds like the floppy drive being axed in the iMac being a 'con' or serial/parallel ports being axed are a 'con'. It's not yet a dead technology, but it IS fading. Every major OS allows over-the-air updating INCLUDING to new editions now, and every major OS (Linux, Mac AND Windows, Linux has had it for a loooong time) has ways to install software for free and for pay from a single, easy, software repository. We also have services like Steam and Origin for games. Personally, if I never have to buy software on optical media again I'll be very happy. For example, when upgrading to a new PC or re-installing the OS, being able to click 'download all' or some such function on various pieces of software, leaving it overnight, then coming back to all my apps? Priceless.
However, just like the days of missing floppy drives and missing serial/parallel ports, it's easy to add if you MUST have it. If you are buying a computer that costs AT LEAST $1,300, why is an external optical drive out of reach? If you MUST have a shiny aluminum one from Apple it's $70, or you could hack one together yourself with a $15 DVD burner and a $15 USB enclosure. Voila. $30 and you have an external optical drive. Shave the $15 for the drive off if you have an old PC with an optical drive in it.
UNFORTUNATELY, I still find myself needing an optical drive once in a while. But just like in the days when I grudgingly accepted a floppy disk from someone behind the times, I just use a cheap external. In my case, I have the superdrive out of my MBP in an enclosure (I have a drive mounted where the superdrive goes).
On the Hard Drive, well, first off, RPM (which is REVOLUTIONS, my dear author!) isn't the only factor determining speed. I guarantee you my 12,000 RPM 2.0GB SCSI drive from a million years ago is much slower than my 5400rpm notebook drive I have stuffed in a USB enclosure. Hard disk density, cache, etc., all matter. That said, it is true that a drop to a 5400rpm drive is a bit disappointing, though if performance is what you're after, then get the 27" iMac OR the Mac Pro!
Finally, I really dislike the 'laptop in a desktops body' stuff. Why? Well because people are so focused on whether or not the letter 'M' graces a component. If this was 1994, I'd be with you, but it's not. Benchmark wise, the iMac with it's 'mobile' CPU, GPU and RAM, will outpace many 'desktop' components used in PC's today. Apple knows that. Apple's engineers aren't looking at the letters, they are looking at the numbers. How fast is the chip? So we have similar performance, but with substantially less heat and less power consumption. That's huge for a lot of customers. There ARE thin desktop PC's that are HUGE in the education and business market that use laptop components (but not nearly as good as the iMac.) Why? Switch 500 CPU's from desktop CPU's to mobile CPU's, and you are likely saving HUNDREDS each month in electricity. Even been in a big computer lab on a college campus when it's 30 degrees outside but the A/C is on? Getting rid of heat saves even MORE power. Although the savings aren't as massive replacing one computer at home, it's still there, and some consumers care about that. But ultimately, tit-for-tat, performance is so close it's hard to really care comparing the iMac to a desktop class system, aside from a high end system, which the iMac is not.
Which brings me to my last point. The iMac has ALWAYS been Apples lower-end consumer device. Originally in the late 90's, it was "i" and "Power". iMac and iBook were the consumer grade, and Power Mac and PowerBook where the high end. All the way back to the iMac's introduction, it used a 233MHz PowerPC CPU while the corresponding 'PowerMac' used a 275MHz CPU with more cache and overall, much much more performance AND upgradability.
In over a decade, NOTHING has changed with the iMac. It's a seldom upgradable, mid-range CONSUMER machine. The Mac Pro on the other hand uses high end desktop CPU's, has limitless (for most purposes) RAM upgradability, and several hard drive bays. Nothing has changed, you've got the consumer (i) and the Professional (now more aptly named 'Pro').
When I read these reviews, I can't help but wonder if these same people would bash a $299 Wal-Mart Acer for not being able to handle Maya rendering or for lacking a solid state RAID array and FibreChannel cards. Granted, the iMac is expensive, but you are paying for some things other than performance alone, like the IPS panel, the build quality, and the service. If you don't think that's a good deal, buy a PC and spend $1300 on a more powerful, albeit cheaper built, system; and a cheap TN panel. Or, if you want a Mac, buy a used Mac Pro which will still outpace an iMac in the types of high end uses that you might need, and it can be upgraded even further down the road to really scream.
If the price is too high for a system of that performance level, don't buy it! Vote with your dollar! Apple is not an evil corporation stealing peoples wallets and forcing them to buy their products. They have a loyal fan base but it's not as big as people think, they nearly went bankrupt in the 90's. Why? The products were more expensive, but didn't really do anything different. The same, beige, plastic, crappy built computers, performance that lagged behind Wintel, and an OS that was ahead of it's time.... a long time ago. People voted with their Dollar.
I don't buy Apple products for cutting edge performance at a bargain price. I build homebuilt PC's for that. Works great. Reliability isn't always great and sometimes I have to replace parts, Windows is definitely not Mac OS, and they are power hungry, hot, and ugly. But they perform well. But my other machines serve other excellent purposes, like a MacBook Pro; a laptop with a truly excellent battery life that is light, cool, and performs excellently. If I was in the market, I'd buy an iMac, though I think I'd rather have a Mac Pro. But to me the iMac's performance, if you look at the numbers and not dwell on the letter 'M', is just fine, and the low power use and low heat IS nice. I've been more conscious of my computer power usage and trying to use lower watt parts in my builds, and it's made a difference on my monthly power bill. A computer that does everything I ask it to do but saves me money? What the heck is wrong with that?