I suspect that if they tried to write an app to suit any device that you might want to put it on by downgrading the software for the hardware, the app size would be so large people wouldn't want to waste the phone space to install it. So if you had a game that was 2MB on the Galaxy after incorporating all the other possibilities that same app might be 15MB. Those numbers were just pulled out of my ... eh ... hat and I don't know how realistic they might or might not be. It wouldn't take long to fill up the available space on a phone if all the apps were written that way. Also, don't forget, its not just the OS version and the hardware; the Carrier also weighs in on the phone also. So Phone X on Sprint is more than likely fundamentally different than Phone X on Verizon.