Apple gets all proprietary

I knew that Apple was wanting people to use the iTunes store to buy books for the iPad, but apparently they're really clamping down now. The changes don't seem all that major, I guess, but you apparently have to now leave your reading app, go to the appropriate store, buy the item, then load it into your app, because nobody wanted to pay a 30% cut to Apple for allowing in-app purchases without using the iTunes store.  I don't know how this will play out; it's not really terrible, just inconvenient.  But for iPad users, I wonder who will get the blame: Apple or the various ereader companies that are trying to avoid paying more money?