I think how reliable an update is, how long it takes before an announced update is actually available, and how frequently updates occur all play a role in which OS consumers buy. The iphone has the least problems with updates, the updates are available within a few weeks of the announcement, and they are quite frequent (1 major update per year, with several minor updates in between). Yes the iphone is boring, but at least it works.
Oh I love the iPhone. Had one myself. But I know the general public is stupid and most do not research products before buying them. In the phone world all people know is either Android or Apple. And we all know Android isn't selling out the butt because of its "uncomplicated updates"