How exactly are you defining "junk"? I think Apple should allow all apps, beyond those that are malicious or overly resource intensive, and let the market decide what defines "useless crap". I suspect most of those .99 apps are developers getting their feet wet learning the system of how to put a paid app up which is why they tend to drop off rather quickly but that doesn't mean they shouldn't be there. What I find more annoying than anything about the app store is that Apple thinks it can be the arbiter of taste for their users when it comes to 3rd party applications.