Require a comment when down voting a q/a post

When looking thru the Q and A topics i see some posts are voted down. I think it may be halpful to not only the owner of the post but also everyone else if it was required to post a comment as to why the post was negitivly commented on. (this may help prevent posts from being negitivly voted for jealousy or just no reason at all) or have a voting details link showing who voted positive and negative?

This may also apply with a positive vote as well.

I am curious what everyone else think about this thought