I know that downvotes are anonymous, but I wonder if it would be good practice for people who downvote questions or answers to provide some explanation or suggestions for improvement?
I ask because it is common for people to ask "Why the downvote?" (I just recently tried to give my own suggestions for improvement in response to such a question), and in the cases where people would legitimately wish to improve their answer/question, it seems an explanation from the downvoter is warranted.
It's your right to downvote when and if you see fit without having to explain yourself or disclose your identity.
That being said, if you have a specific suggestion for what could be changed to improve a question or answer, give it. Whereas if your explanation is merely, "I think the question/answer sucks," I would suggest remaining anonymous.
We will never be able to require explanations for downvotes; it is and always will be a courtesy, unless the folks who run SE decide to put something in place to force it. Even if we wanted to do something like that on just our site, the mods don't have that kind of power (to build such a mechanism), nor can we see who votes for what should we want to enforce it manually.
That said, I have not seen this to be a significant problem. When something is downvoted, especially more than once, usually at least one person leaves a comment why. If there are no comments and many downvotes, it is usually (and ought to be) explicitly clear why the post is being downvoted.
I believe that down-voting should always be explained. This limits the amount of retaliatory down-voting that can occur. (And don't be so naive as to believe there is no retaliatory down-voting on this site).
In addition, IMO down-voting without an explanation is counter-productive: This is not a popularity contest or a political game, it is a site designed for people to learn on, and to educate with.
If you find something worthy of a down-vote, what do you lose by explaining yourself? You will either educate the one you down-voted, or perhaps get an explanation that will make you change your mind.
