If enough amazing apps come out that require an App.net account to use, people will get on it. Think about it like this: if Netflix came out with a developer program whereby devs could create new video-watching-related apps that required a Netflix account, guess what? They'd probably do just fine because millions of people already have Netflix accounts. App.net is starting from scratch, yes, but if they can build up to a few hundred thousand or over a million paying users who perceive value, this thing is frankly a no-brainer.
I think the logic behind the feedback system is pretty good too. A lot of users won't bother submitting feedback, but the ones that do are already motivated to submit feedback and therefore reward apps they like. So it's in the best interest of devs to create apps that delight their users. Win-win all around.
The difference is that apps aren't what attract users to Netflix. Movies attract users to Netflix. That lets Netflix build up a base of users, which then makes it an interesting platform for apps.
App.net, on the other hand, is just glue to connect applications together. Outside apps, there is no "there" there. So it suffers from a chicken-and-egg problem that Netflix does not -- they need users to attract developers, but to attract users, there have to be developers building attractive stuff.
Probably the easiest way out of this conundrum would be if they could entice some celebrities or other high-profile figures to ditch Twitter for App.net. They would create streams of content people want to read, which would attract their fans, which would attract developers. This seems a bit contrary to the App.net "we're just an API" philosophy, though.
I anticipated your response (not you personally, the point you're making). I agree App.net needs top-notch personalities with interesting content or discussion. I don't agree with the "no 'there' there" premise, however -- I've already found that in spades. But I'm of the tech crowd. If they can draw more people from the margins of the tech world who can pull their communities in, there were be a lot more "there" to go around.
I think the logic behind the feedback system is pretty good too. A lot of users won't bother submitting feedback, but the ones that do are already motivated to submit feedback and therefore reward apps they like. So it's in the best interest of devs to create apps that delight their users. Win-win all around.