Downvotes are kind of outside of the community sadly and part of a broader issue with hive overall. Downvotes are an essential part of making proof of brain work but getting a downvote leaves such a bigger mark than getting an upvote that it creates constant fights, so at the end of the day few people actually downvote when on other social platforms like reddit, downvotes are very common. Overall I think this needs a deep redesign of the way post reward work, we tried the social layer (eg letting 25% of downvote power to be free) and that hasn't worked all too well.
Anyways that's a much bigger topic than this change / comment and I doubt adding a reason for downvotes would help that much.
RE: Changes coming to a community near you !