Yes, the store costs money to maintain.
Yes, support for hardware and software costs real money.
Yes, boot camp costs money to maintain, i.e. upgrading it to Snow Leopard for one.
Yes, creating an API and maintaining it would cost money. And to do it for the competition...
Yes, OS X can be used without iTunes so it is still just an App.
Wow, were these real questions? No hostility is meant by this post, though it comes across that way.