People in general care about karma points and don't like the score to go down. People also take downvoting personally, and when someone comments and explains why they downvoted, they're susceptible to "revenge downvoting" by several accounts (owned by or related to the one who was originally down voted) on many of the downvoter's comments across threads. This in turn would cause distress to the downvoter.
As long as HN has a number assigned to everyone that people interpret as significant, I'm completely for downvoting without any explanations. The fact that both upvoting and downvoting are anonymous (to the one getting the votes) ties directly with this, IMO.
As long as HN has a number assigned to everyone that people interpret as significant, I'm completely for downvoting without any explanations. The fact that both upvoting and downvoting are anonymous (to the one getting the votes) ties directly with this, IMO.