I mean - imagine Vista, or Win 7 going on the phone, just with a new touch UI framework added. It simply wouldn't work, couldn't work, would be impossible, beyond the reach of the richest software company in the world.
Sometimes, good engineering does pay off, and ultimately one could say that iOS is a direct result of good engineering. Every time the iOS wins it's a win for good design, and for object oriented programming.
That said, the dark side of being so far ahead of everyone for so long is a severe case of NIH syndrome at Apple. Those times when others surprisingly better Apple, Apple takes a very long time to catch up. Dev tools are the best example with XCode 10 years behind Eclipse. MobileMe Mail is perhaps another one: MobileMe Mail is similar to Mail.app on OS X - but Gmail is way better than that, and has been pretty much from the beginning.