This.
I've made a few downvoted comments. One was flagged and removed, and drew a rebuke from dang (on the Slashdot sale story, as it happens), and though my initial comment was perhaps to telegraphically negative, there was substance there.
Also: while it does little good to complain about downvotes as the OP, I've occasionally noted comments in which the downvote brigade strikes me as emotional and/or hivemindish. I'll also frequently drop to the bottom of long threads and upvote comments I feel are getting undue negation even where I disagree with the contents.
This last: so long as the sentiments seem grounded in facts and reason, I don't believe any comment should be greyed.
As for moderation in general, it's a Hard Problem. HN is coasting largely on a community that has good, though far from perfect tendencies. I've seen far too many discussion systems be overwhelmed by the combination of toxic social dynamics and poorly conceived moderation systems. HN suffers only one of those handicaps, for now.
More on moderation:
https://www.reddit.com/r/dredmorbius/comments/28jfk4/content...