They have tried this, I used to work for a company that makes an app for Android and iPhone. The app isn't great in itself, but it's part of a bigger service, a

They have tried this, I used to work for a company that makes an app for Android and iPhone. The app isn't great in itself, but it's part of a bigger service, and was even featured in an iPhone ad at one point. Microsoft said that they'd pay $100,000 towards an app for WP7 but we said no. It sounds like a great deal, but the problem is that making the app is just the first part. You're now on the hook for maintaining the app, providing customer support, fixing bugs, adding new features etc... If MS provided a guarantee that they'd pay for the ongoing support costs, that'd be one thing, but I'd imagine that would get very expensive very quickly.