The quality of discussions is what brings me to HN, and IMHO the quality is poor; it's just better than the alternatives. The vast majority of comments aren't worth my time (or anyone else's, but they can speak for themselves). In other words, there is much room for improvement and I hope that is Dan's focus. I happily would accept unfairness, and suffer its slings and arrows myself, for a higher signal-to-noise ratio. I'd happily lose a few good comments in return for of better quality overall (i.e., false-positives are not really a big deal - so what if my good comment occasionally gets voted down or otherwise buried).
By prioritizing quality over fairness HN can best distinguish itself from a million noise-filled alternatives where 'rights' are the priority. Everyone has a right to their opinions, but not to my time.
EDIT: Several edits to explain myself better.