(Incidentally, I would still love a feature where I could review recent upvotes and downvotes applied to me... to the extent that karma is intended as feedback for the poster, it helps to have some way of associating that feedback with the actual thing being evaluated. Knowing that I said something at some time that someone wants less of on LW doesn't really help me much.)
Definitely this.
I just found out that a new website feature was implemented 2 days ago. If a comment is voted to -4 or below, it and all replies and downstream comments from it will be hidden from Recent Comments, and further replies in that subthread will incur 5 karma points penalty. The hiding, but not karma penalty, applies retroactively to comments in that subthread posted before the -4 vote.
This seems to be worth a discussion post since most people are probably still voting things to below -3 without knowing the new consequences of doing so.