Just a note: When talking about iOS and Android devices, yes.. OS updates are sort of free.. but in many cases, you simply can't upgrade older hardware to new OS's. For instance, with android devices, your phone carrier has to issue the update, and they typically have to support it.. you are usually lucky to get one major revision before they no longer support updates.
iOS has been a little better, but.. for instance, the iPad 1 was basically dropped from iOS 5, and iPad2 will probably not see an iOS 8. What's worse is that most of the apps stop working on the older OS's, so you can't typically even get new apps if you're running an iPad 1 anymore...
I'm already seeing the effects of iOS 7, and already there are apps that no longer work for iOS 6.1.2 which I have cos I'm Jailbroken. Usually if there is no Jailbreak fort an iOS, I don't upgrade UNTIL there is one.
My policy is that apps that refuse to make their new versions downward compatible get deleted pronto from my device, and if it is something like Numbers/Pages/Keynote I'll stick with the last version that works for my iOS. App Devs that won't do that extra work to make backward compatibility are not worth bothering with.
But for every iOS app that refuses to make backward compatibility, there are about 15 apps that DO. Apple does this to force you to get their new iOS, so I bear with them.
As far as iOS in general, since the OS of any Mac computer or device is considered part of the hardware, you have to put up with their limitations.
iOS downloads are free, but they are NOT free because I cannot at this time, delete my iOS and install 4.3.3 or 5.1.1 in there, or even any version of iOS 6.
And why do they do this? So people won't revert back to an earlier iOS so they can JAILBREAK. the whole damn thing is stupid, but the eVad3rs, Redsn0wers, and Absinthers have kicked every iOS's ass since the first iOS, and they'll beat the crap out of iOS 7 too. So I'm not worried about it.
The problem with iOS is that it can only be installed via iTunes, and that's where Apple has their CHOKEHOLD over you. I wish someone would create an iOS installer that can totally bypass Apple stupid SIGNING polices. There;s gotta be a way around it, if I were an Apple programmer, I'd work on it.