They're a middle man providing a service that has taken different forms in the past. You can be cynical, but realistically their goal is to make a profit by providing a service which has it's own costs to cover. How much would those developers have reaped without their service?
Lots, lots more. If the Apple their devices weren't monopolistically locked down, or the store was an open market.
Really, you think its worth their cut, just to operate the store? How much overhead would it take you to put up a web store? They only get away with it because they aren't Microsoft.
