In all due respect, I agree with @williambanks. Your proposal bastardizes the downvote as its intended functionality to be a reflection of opinion of quality of the content or of personal preferences. To fix the voting algorithm, we depend on the developers of the Steem blockchain protocol to do that.

Your intentions are perhaps admirable to have a less lottery style voting reward algorithm, but the way to achieve it is not to abuse the meaning of the downvote feature. We should instead ask the developers to consider changing the algorithm.