Closed platforms, by which I mean any hardware, software or combination, that charge developers to list their apps for download, will naturally stifle open-source software and hobbyists. For a project run by a worldwide community of like-minded volunteer geeks, nobody in particular would be responsible for putting up the cash to list their project on the market or app store, so it won't go there. Some very large projects might be willing and able to jump through the hoops and pay their dues, but that's not what the app store model is set up to do. And when you are set up only to accommodate one particular type of innovation, you've already lost.
Mokalus of Borg
PS - Then again, I do have positive things to say about app stores.
PPS - I'll save that for another time.