Well, I'm a small independent developer and I disagree. The 30% is fair for what is offered from Apple's side: tax documentation, billing arrangements in different countries, visibility on the App Store, detailed metrics on usage, and more...
I dislike how 'independent developers' are OK with this until they suddenly become huge companies with million dollar budgets (and profits) - then it's suddenly 'unfair' because what they're paying Apple now amounts to millions of dollars (even though it's still the same 15/30%). It's disgusting actually, and I'll be really annoyed if the big developers pay less proportionally than the smaller ones - that's really unfair (you know, like the US tax system... great model that).