Yeah, I get downvoted often. Coininstant and the account you mentioned as well. sometimes even from some accounts that have a nice amount of stake.
Both upvotes and downvotes are valid. I just accept the votes and move in. I consider a post open for people to express their opinion on for 7 days and the rewards become mine when the post closes.
Sadly some have behaved so childishly over some downvotes they have trained the entire community that downvotes are punishments or bad, when really all it is a a way to raise the value up or down using stake. :)
I think it will settle down as people understand they are a normal part of curation. If we can't normalize them I honestly think Steem will fail.