Well, the more fundamental problem is this business of Apple taking 30% of everything. I am not disputing their right to set the rules within their own ecosystem. No issues whatsoever there. It's their product and they deserve to do as they wish.
Having said that, that is not to say that I agree with their decision. For almost any business 30% is a huge percentage of gross. In most cases the margin is dangerously close to or lower than this number. What this means is that there are a whole host of goods and services that cannot be offered through the platform due to their fee structure.
Then again, it's their sandbox and their rules.
This is somewhere where companies such as Microsoft could make a significant dent if they keep their paws off the content creator's revenue stream (or take a very small bite). In my opinion a 5% "finder's fee" is reasonable. If they handle the financial transaction then there's the customary credit-card billing stuff.
Two things that iOS does not offer that someone could offer:
1- Less intrusive cut taken from revenues, as discussed above.
2- Open access to I/O, file system and various resources that Apple locks down tight.
As an example, if I wanted to design a general purpose iPhone to RS-232 serial cable, well, it's impossible. You can make one married to a specific application but you can't make one that's a plain-old open-to-all serial port converter. There are tons of applications in industry that could use such a cable, but Apple chokes the hardware side so tight that even something that simple is impossible.
Another example is the choke-hold on proprietary Bluetooth. I'd love to create apps for kids to use to control their Lego Mindstorms with an iPhone/iPod. Mindstorm blocks have built-in Bluetooth. Apple's version of Bluetooth, for various technical reasons, is not compatible with "normal" Bluetooth. The only way to do it is to purchase Apple-approved Bluetooth chips and get permission to build a device subject to their approval...but you can't build a generic device. In other words, you are building a specific speaker that uses this chip and these codes to identify you and the app. Period.
I feel that companies trying to compete with Apple are not seeing the elephant in the room: Closed vs. Open.