As noted by binarycrusader, no approval is necessary. It's just like signing a Windows application (also a damned good idea) and counter-signing it with Microsoft's cert. Both of these things make it so that your app can be flagged if you demonstrate that you're dangerous. The main difference is that Apple has it somewhat easier because they are the CA for the app certs.
As far as who develops apps for "classical" computers…there's a lot of us out there, because they're not going away.
As far as who develops apps for "classical" computers…there's a lot of us out there, because they're not going away.