I very much agree that unmarked voting systems like HN's do a really poor job of keeping comments "high quality." Everyone has a different definition of quality.

I understand that there are UX challenges to adding different kinds of votes, but I totally agree that the UI affordances we have right now make conversation harder instead of easier.

I wonder if separating "quality" (vote + or -) from "reports" ("excessively rude", "inappropriate", "off-topic") would be useful. I do think that people can be excessively rude and useful at the same time. Edit: So, this would change from "-3 points" -> "-3 points [rude: 3, off-topic: 5]".