What app.net can do is offer you as a developer the credible promise that whatever you build on it will not be shut down because it conflicts with business decisions made 1, 5 or 10 years from now.
This of course trickles down to the user, since you are virtually guaranteed that there will be new clients for as long as the service exists. With Twitter you are virtually guaranteed that no new client ideas will see the light of day unless they come from Twitter themselves, and those will all be designed to increase your usage of the service with any increased utility merely serving as the hook.
I do understand this, and would like it to be true. But until at least one application actually exists that twitter won't or can't do, this is all promises, and those apps (which I hope aren't limited to user clients) are, in fact, vaporware. To a user, this $50 isn't today buying them anything they can't get from twitter, which is why app.net might not get funded.
Well this has only been promoted for like 3 weeks, so give it a minute. There's a chicken or egg problem, if no one buys into the dream before it's reality then it will fail.
It doesn't take half a million dollars to come up with one single actual demoable application that does something twitter won't or can't do. The point of this thing is supposed to be better apps. Fine, show me one, and I'll pay $50 to see more.
This of course trickles down to the user, since you are virtually guaranteed that there will be new clients for as long as the service exists. With Twitter you are virtually guaranteed that no new client ideas will see the light of day unless they come from Twitter themselves, and those will all be designed to increase your usage of the service with any increased utility merely serving as the hook.