Well, it's a good idea, but it needs a big, fat "hey, this might/will probably break stuff in the app you're authorizing" button. Apps usually request that stuff for some reason, and the vast majority of users don't have enough understanding of the systems to know which permissions are safe to revoke.
Best case, things silently break and the user doesn't care. Worse case, things break and the user blames the developer and malign the application. You know how important the star ratings are in the mobile markets? You know how much effort developers put into managing the user experience, knowing that their app's success lives or dies based on their ability to keep from offending the luddites among their userbase?
This is great for power users who understand and accept the risks inherent in doing something like this, but it's an awful idea for just about anyone except developers who understand what those permissions are actually used for.