[pwny]

I don't see why Apple is so reticent on this. They wouldn't lose anything by letting users replace most default apps.

Of course, they can't allow the replacement of the App Store and continue with their current model but a user that already owns an iPhone and replaces the Mail app or web browser doesn't hurt Apple in any way. They'd probably even have more people buy iPhones (and make 30% on the sale of paid replacement apps). I fear it's because of their compulsion to control the experience from A to Z.

(disclaimer: I own an iPhone 4, iPad 2 and MacBook Pro)

I'd wager that some sort of (limited) "intent"-like mechanism is coming in a future iOS down the road, although not 6 and probably not 7.