at absolute minimum i would say when you have to do an admin task twice through messing with the database or something is when you should probably add an interface for it, guessing what tasks the user (or reality) will screw up is hit and miss at best.

some of these tasks when caused by human error the better idea is to make it more difficult to break the system than just easier to fix it and allowing the user or admin to fix it on their own hides the issues away