Improving negative curation, A downvote button Vs. flag explained. [UI improvement]

Here's my vision of a downvote button at UI level.

The new downvote button has the same effect as the current flag on the blockchain but it's maximum strength is calculated in the UI so that it can only bring the post/comments to $0.00 and not below.

The new flag button has warnings about it's usage similar to what we have now but without the "disagreement on reward" (use downvote for that) the interface would also encourage, if not force users, to leave a custom comment or select a preset reason to let the author know why his content was flagged.

Reasoning :

1. Not enough people are down-voting so not enough organic content discovery is taking place.
2. Votes can too easily be sold for liquid money without any regard for content quality.
3. New people getting flagged think someone's is accusing them of wild claim like of Fraud or Hate-speech... drama ensues.
4. It is problematic right now to know what vote weight to use to bring a reward to zero but not below and unintentionally hiding content behind extra clicks on Steemit.com and having to deal with one more uninformed claim of censorship than a disagreement on reward warrant.

This solution is for sure not perfect as bringing a post to 0.00 doesn't mean someone won't upvote it later and without being able to see orders of downvotes on a block explorer it's impossible to tell which user brought the post from $100.00 to $0.00 or from 0.00 to -$0.05

On that subject I'd like inputs on what could be possible disadvantages and technical challenge if the blockchain would not to forgo previous voting power when either incrementing a positive vote or reducing a negative vote ie: from +10% to +20% or from -10% to -20% ?