One of the comments on that page correctly states that Apple product owners buy more than Android users (on average, I'm sure there are exceptions). That's an important point, but I'm quite uneasy about the way Apple seem to think they own the user and hence have the right to skim a percentage of whatever they spend.
Apple seem to want to have their cake and eat it, if they allow an app at all the publisher should be free to use whatever payment system they choose (as long as that payment system is trustworthy). Enforcing the rules they have will push developers to bend the rules (which is more likely) or to go down the web app route (a major point of Apps is to make life easier when launching... I doubt we'll see this tagline "Kindle, there isn't an app for that") - I can't see 30% being acceptable in many verticals.
This is not a good situation.
