I think this is a great idea.if you like the user and add them that will give them the privilege to comment you.But if you don't add them you can't comment them.What I'm trying to say is that you can only receive comments from people you like.If you see a user cursing at everyone you don't add them.Then that way you don't have to put up with their cursing.
Why WOULDN'T moderators like it? They get 5x spam 24/7!
Well, I guess moderators wouldn't need to use it, since everyone needs feedback, help, and so forth. But we smallies need it, we don't have to put up with 3 word people every day!