As I said, it can afford indies some legitimacy.

I'm not arguing that either is good, but I think there is a fundamental difference. Apple is reacting to the threat of regulation, which is at least theoretically aimed at protecting small business owners. Valve is fundamentally competing for the business of large companies that actually can afford to forego the exposure Steam offers.

I'm not sure that the App Store's position is as stable as Steam's, either. I don't really have a clear sense of what impact it would have on their sales if Humble Bundle could sell iOS games.