DEVELOPER: We spent months working on this. Here's your fees: One Arm, One Leg. Certify our app, please!
PLATFORM: Please hold...We're sorry, but your product does not comply with our guidelines. Goodbye!
DEVELOPER: Why are you rejecting our app? We were very careful to do everything you asked us to!
PLATFORM: Your app does not comply with the guidelines.
DEVELOPER: But we think it does!
PLATFORM: But we think it doesn't! And what we say, goes.
DEVELOPER: But what did we do wrong!
PLATFORM: You didn't comply with our guidelines. That's all we can say.
DEVELOPER: Can you at least refund our application fee?
PLATFORM: Doing that would not comply with our guidelines.
DEVELOPER: Do you have any idea how much it cost us to have several developers working on this product for months?
PLATFORM: That's your problem, not ours. Have a nice day!
DEVELOPER: (obscenities)
People who are willing to put up with this kind of garbage are writing iPhone apps. There is little doubt in my mind that the Windows Store will be a similar experience from the developer's perspective.
I have no special knowledge about this, but from watching MS since their early days I don't believe their goals are quite as crass and simple as you describe. My guess is their internal narrative is more along the lines of:
"A large share of market is shifting away from PCs to smartphones and tablets. Big factors in the success of these devices have been the simplified UI and the centralized app review processs to enforce a baseline level of quality and help prevent malware. Apple and Google have major businesses built on their respective app stores. With a billion or so Windows users there are good reasons to think that our app store could make the others look small in comparison. 30% is similar to what the other app stores are taking and it will be a lot easier to reduce this number later than to raise it."
PLATFORM: Please hold...We're sorry, but your product does not comply with our guidelines. Goodbye!
DEVELOPER: Why are you rejecting our app? We were very careful to do everything you asked us to!
PLATFORM: Your app does not comply with the guidelines.
DEVELOPER: But we think it does!
PLATFORM: But we think it doesn't! And what we say, goes.
DEVELOPER: But what did we do wrong!
PLATFORM: You didn't comply with our guidelines. That's all we can say.
DEVELOPER: Can you at least refund our application fee?
PLATFORM: Doing that would not comply with our guidelines.
DEVELOPER: Do you have any idea how much it cost us to have several developers working on this product for months?
PLATFORM: That's your problem, not ours. Have a nice day!
DEVELOPER: (obscenities)
People who are willing to put up with this kind of garbage are writing iPhone apps. There is little doubt in my mind that the Windows Store will be a similar experience from the developer's perspective.