As an APP developer, I can tell you that Apple makes it pretty darn difficult to support older OSes. Xcode all but forces you to add "retina iphone5 this" and "Arm7 that". That is why new APPs (and even many older ones that ran fine on OS4 or 5) require OS6 to run. Kinda sux, but that's how the game is played. M$ invented it, Apple is simply perfecting it as they are always keen to do.
-iamthinking
2 things:
1 - with so many users keeping up to date, why would you care if its difficult to support older OSs?
2 - it's not difficult to support older OSs? Just because it defaults to those settings when you make a new project doesn't mean you're forced to use them.