The obvious advantage of Apple controlling everything you can and can't do with your phone, plus being the only manufacturer of hardware and software is that the idea of "system requirements" for apps can be reduced to a handset or OS version number in the worst possible scenario. In the Android space, different phones have different capabilities so it can be harder to determine if a particular app is going to run on your phone or not. At that point you get into the realm of real system requirements and possibly compatibility checkers, and by then most users will throw up their hands in confusion and go buy an iPhone.
Mokalus of Borg
PS - Again I go on about the iPhone.
PPS - You know I'll end up with one eventually.