I've heard various ideas such as limiting it only after mods have expended their points (this will require implementing a cooldown to prevent a user from getting points again too soon). I want to hear your feedback, and I'll roll together something for the next major update of the site. Leave your comments
Very good point. This post just got put in my scratchpad of things to keep in mind on working on this. The biggest problem is just having a karma system at all acts like a challenge (when we started, there was a race between the staff to see who could hit karma cap first).
That being said, for things like earning XP, I didn't intend to have it just earned by posting; you have to post, and get modded up to get XP; you don't get points for posting low quality stuff; it has to get upvoted for it to count with stronger XP award if it gets to +2/+3/+4/+5.
This might also be the way to get metamoderation to work, and moderators can earn XP by getting their moderations voted on, and metamods get XP for metamoderating itself. I don't want to tie the metamod data into the mod algo until its transparent to the user (black boxes are bad), but having a way to get feedback is a GOOD thing.