I got some down votes recently. When someone gives me a down vote and describe his logic, somehow it helps me to get the point and improve. But sometimes no one said nothing and just gives a down vote. When, I couldn't find any reason behind the down vote, it feels frustrating. I know, when any use down vote any question or answer, there pop up a window and tells to describe the reason. But not every one takes it seriously. So, I though about it, if it can be mandatory to describe the reason of down voting, may be it will be good for users.
If you provide links to your downvoted answers, we can probably try to find explanations.
Personally, I would not make it mandatory to write a reason for every downvote. Generally, I try to comment on my downvotes if I think there is a chance for improvement but some answers/questions should be downvoted as fast as possible and a mandatory essay is not going to help.
I can only recommend not to take a few scattered downvotes too seriously or personally.