To throw a couple of ideas into the "tech solutions" pile, I wonder what would happen to the quality of comments in a community if a mandatory 1 minute delay was put in before the text area would appear. This would I think have two benefits: 1. it would for commenters to think about what they were saying for at least a minute. 2. It would raise the barrier of entry to the point that posting a worthless one liner doesn't seem worthwhile or satisfying.