OMG, look at that! My PC runs Win7, my wife's still has Win Vista, and at work a lot of them are on XP! Not to mention that there are 32 bit/64 bit versions, the Pro/Server/Home/WhatNot editions... How fragmented is that?
Every OS in the world has some devices that run certain versions better than others. Older hardware is left in the dust because that's what progress means. Funny how iOS users act like their farts don't stink, when the truth is their devices are subjected to the same phenomenon like the rest. Stating that the iOS devices all run the same OS version (while at the same time they admit that not all the functionality is preserved) is a failed attempt to deny the same fragmentation that plagues every single OS.
If the device works as intended that is enough in itself. Some people want the latest (but they don't get the greatest at the same time, because their device is not supported), but most customers are happy their phones work as intended. Guess what, everyone that wanted ICS or JB on their phones already got it, one way or another. The rest don't care, or they would have already upgraded their phones.
iOS actually has the "reputation" of crippling the older hardware with their "upgrades". Remember when iOS 4 tanked so many iPhones 3G and 3GS? What used to be a nice and smooth experience suddenly became choppy, unresponsive, in some cases unusable. Then Apple wised up and instead of pushing the new OS, they pretty much changed the "about" section to say it runs the latest OS, even though was a crippled version, with a bunch of apps missing. One can do the same on any Android phone by editing a file.