I personally wouldn't waste my time asking for the reason you recievedreceived a downvote. If you receive a downvote in the future, take it upon yourself, to improve the quality whatever you submitted. This also goes for asking the reason a flag or an edit proposal was declined, just accept the feedback that is provided (typically canned responses) the best you can and move on.
As for the reason, I am submitting this feedback, you asked nicely (by asking this question instead of submitting a comment) that the downvote is explained, so I am doing that exactly.