Kinda like what Java Verified and Symbian Signed have been doing for years?
A cryptographic signature (with an Apple-run signing authority) also ensures that your apps haven't been tampered with by a third party and (in theory) should let you track down the owner of an app if it turns out to be malware.
What if Apple were to start assigning a reliability or confidence score to the app/developer and amending the approval process to take this score into effect?
New apps/developers need to go through the standard application approval process as it is now. As applications are approved/rejected, their score changes based on the results of the testing.
As developers release updates to a given app, the approval process of that app is adjusted based on the confidence score. e.g., an app with a high confidence score would just automatically get approved (or maybe just a quick static analysis) whereas one with a medium score might just get a quick cursory testing.
Additionally, to keep people from trying to game the system they could add in some random full testing of apps regardless of their confidence score.
That way users have the choice.