I agree with Andy that there should be separate +moderator address for moderators (who aren't owners); and would also suggest that use of these (+moderator and +owner) addresses should be controlled by seperate (one for each) moderator privileges.
But will also agree with Marv and Bruce that this would be an extra (and probably much less trivial) change, which will also have implications on the way that at least some groups run themselves; and so should be raised and discussed as such.