I think it would be nice if the people who downvote comments were exposed. Two people in a bad mood (holding a grudge against you, etc.) are enough to make your comment (and the whole discussion tree) virtually disappear. A recent example for this: https://lobste.rs/c/4wb5vy Though a bit cynical, as kghose says himself, there is no direct reason to downvote it and hiding the subtree as side effect.
I think exposing downvoters would require them to think twice before clicking that button. It would also fit the lobsters style of transparancy, imho. It could lead to a downvoting contest, but there isn’t anything to prevent this aside from common sense.
(Extra transparency: I’ve been downvoted on two comments, the first was a reply in which I’ve stated that a comment didn’t deserve 0 points. After that comment was downvoted into hiding for “trolling”, I responded with a second snarky comment, which also got downvoted but I expected that.)