Must disagree. There are almost no appreciable differences between iOS 4 and 6 (except demand on CPU). Windows Vista to Windows 8 is a massive performance jump. Android 2.2.2 to 4.x is the only huge leap forward I can think of. Windows 8 and RT are introducing a new paradigm so there will be some heavy refinement going on. No reason however why this couldn't happen with usual updates (the most recent RT update resulted in a significant performance hike), but it is as Goodbytes says: everybody now expects yearly upgrades --especially with mobiles. If Microsoft wants OS consistency across all devices it has to adopt a relatively synchronous update schedule.