With all this talk of larger screen iPhone 5, can't iOS 6 solve dilemma?

I am not a computer programmer, so when it comes to terms like "vector graphics" I only vaguely understand how they are implemented in an OS. Wat I do not understand is why is apple so hung up on the original iPhone and iPad aspect ratios? So much so, that it seems they've boxed themself into a corner now that it is evident that the next iPhone will need a roughly 4inch screen to keep up with the times.

What I don't understand is shouldn't apple be updating iOS so that they can solve this, shall we say "anti-fragmentation" issue so that they are no longer constrained by the 2007 iPhone and 2010 iPad aspect ratios? Up till this point, apple has done the logical thing and doubled pixels, but now we are hearing about a "mini iPad" at the original resolution as the iPad 1 and 2 to aid in a smooth developer transition.

It just seems to me Apple should be working towards an ultimate solution to the problem at an OS level instead of just dancing around eye issue with math. I mean, OS X scales based in screen resolution, you're telling me this isn't achievable with iOS? Why? Can someone explain?