I believe that there is a simple solution to this, short of Jason Calacanis' great idea of just giving is an "allow unsupported apps" button. My solution is this: Hey Apple, you know those NDA's you love to make your faithful sign? Well agree to go the other way here too. What I mean is "sign" an NDA with developers and then create 2 approvals. Concept and Code. That way a developer could submit a concept for an app, and if approved they have exclusive rights to build it. This way developers would know that the app wouldn't be blocked for concept after spending a lot of time and money developing it.
And now that I am thinking about it, Apple could use a system like this to find out what kind of apps the users really want. They could allow non-developers to submit ideas, and let developers that want to build those apps do it. They could even reward the person who submitted the idea with part of the app revenue. (30 percent Apple, 20 percent idea, 50 percent developer?)
Although does apple really care about whether the users get the apps they really want?