There has been enough nastyware on Android platforms to at least somewhat justify Apple's approach. Sandboxes have a way of springing leaks.

I was 100% on the opposite side of this debate when the iOS SDK first became available. (This was what I had to say about their limitations at the time, if it lends me any street cred: https://www.youtube.com/watch?v=sVkqbycvuKw ).

But at this point the restrictions I objected to have mostly been lifted, to the point where they don't interfere with the vast majority of developers who aren't looking to do something slimy. It's very nice to be able to download and install apps without having to wonder what the developer's real agenda is.