Apple just released the SKStoreProductViewController in iOS 6, which allows a user to access the app store from within an app (like a modal view that slides up from the bottom). In fact, the WWDC video presenting it uses cross-promotion of apps as its first example use of the view controller. If you're right about Apple's motivation, I would think using the SKStoreProductViewController would be an easy compromise for developers to take.
Edit: If you haven't seen it before, this https://www.dropbox.com/s/eytnivsz5ft43mh/iOS%20Simulator%20...