When up/downvoting a post (particularly for downvoting), it is often useful to leave a comment explaining why you are doing this so that the post can be improved, or so that the poster knows why the voter thinks the post is bad.
However, the only way to do this at the moment is to post an actual comment, which removes the anonymity of the vote; there are many situations where a voter may not want to do that.
The potential solution:
When a user votes on a post, they are given the option to add an anonymous comment to the post to explain their vote.
I was hoping for some input on this suggestion, and whether others feel that this problem is worth addressing.