See: http://meta.stackoverflow.com/questions/135/encouraging-people-to-explain-down-votes for a related discussion
I have read the other post too. Some good stuff there. I personally like the drop down suggestions for the thumbs down but telling the poster it is “wrong” for example does not help anyone. We still need a detailed comment. It would be nice if you could force the user to comment but that they know it will be anonymous. Is this possible to do?
Really complicated to change this and I kind of dislike the explaining feature, to be honest