MG Siegler follows up on why this move makes sense, is not in fact evil and this:
Apple is betting that the allure of being tied into their incredibly efficient iTunes payment ecosystem (along with its 100 million + accounts tied to credit cards) will outweigh the downside of having to pay them a 30 percent fee. The same 30 percent fee they currently take from the thousands of app developers collectively making billions of dollars off of the App Store. And the same 30 percent fee they currently take for all other types of in-app purchases.
As I told a couple of you who emailed about this: Apple is providing the billing, payment processing, infrastructure, and willing/able buyers for only 30% — seems like a steal to me.