Freedom for developers provides freedom for users. How about a different home screen? With Android, the user can play with that. With the iPhone, they cannot. Not because the iPhone cannot technically support different homescreen layouts, but because Apple won't give developers the freedom.
Locking down developers necessarily locks down innovation. And that hinders the users.
If the carrier allows. My point is that even though the core of Android is open source, the users DO NOT get the open source experience. Between proprietary closed-source apps making up much of the standard delivered OS experience, proprietary user interfaces (both of which have resulted in legal threats against Android developers) and hardware locks, you aren't that far away from the iPhone.