Well, first of all... why do we need groups at all? Seems like the subject filters don't work to start with... the groups overall, to me, seem pointless. Other than when checking out a new profile and seeing what they're into.
But how about simply having a suggestion box (like the Question Bot) and have someone approve or disapprove of group subjects.
And, I don't think there should be any additional powers to the group creater, as that's just going to create a power struggle and bad feelings that we don't need.