Giving flags more weight is not necessarily the answer. Punishing people for making bad comments is, I think, more important. Equally important is punishing people for upvoting bad comments.
But now it's late here, and starting tomorrow I'm really not going to be here for a while. Good luck PG, I hope you can find a way to reduce the mean-spiritedness fluff, and make HN more pleasant again.
I think this last sentence is very telling. Low quality is only part of the problem. What really makes people want to disengage is having their feelings hurt.