One potential function of a karma system I have not seen mentioned is that it can act as a release valve that gives a person a way to express his displeasure, fair or not. Without that release valve the person might instead write a flame, triggering a flame war. This is in addition to the fact that actual flames are themselves likely to be heavily downvoted. Some unfairly assigned negative karma may be a fair price to pay for relative freedom from flamewars and the tremendous waste of time they represent.
My impression is that critiques of lesswrong mainstream positions and arguments for contrary positions are received well and achieve high karma scores when they are of very high quality. Similarly posts and comments that take lesswrong mainstream positions will still be voted down if they are of very low quality. But in between there seems to be a gulf: Moderately low quality mainstream comments will stay at 0 to -1 karma while contra-mainstream comments of (apparently) similar quality score solidly negative karma, moderately high quality mainstream comments achieve good positive karma while similar quality contra-mainstream comments stay at 0 to 2.
Do you share my impression? And if this is the case, should we try to do something about it?