I’m new to this discussion, so please excuse if this point has been discussed before: Perhaps it would be helpful to allow LW users to send optional (?) and anonymous messages when downvoting. I think, what is inefficient or even harsh about downvotes is that you cannot judge (1) whether the downvoter is actually in the position to judge you and (2) what the exact reason for the downvote is. It’s a bit like the (sometimes anxiety inducing) exercise of reading social cues, but it is in this case even more difficult due to the abstraction to a number.

Edit: Perhaps the downvote could also provide some anonymized information like karma, comment count and account creation date.