The downvote system on Hive is deeply flawed, IMO. I even argued against it in one of my early posts on the subject, because it does have negative effects. But I think it also has some positive effects, despite it being a weak system.
I have been planning to publish a post about this, but my personal take is that a downvote should 'cost' the same voting power as an upvote. If I choose to negate someone else's upvote with a 100% downvote (or replace many minnows' upvotes if I have a lot of HP), it should also replace one of my own 100% upvotes.
You obviously missed the entire Haejin drama where that proved to be at the detriment of those who wish to counter abusive behavior.
I've done that with others before "free downvotes" were a thing and let me tell you this:
It's incredibly stupid to expect someone else to sacrifice curation so "bad actors" won't get anything while everyone else who doesn't care gets their returns.
Even with the compensation programs set up by @steemflagrewards, it was still doing it at delegators' expenses with little to no upsides.
There's a free-rider problem, for sure. But the current DV system is itself ripe for abuse. And it will encourage ideologic DV wars once the ecosystem begins genuinely expanding.
Also, it punishes legitimate curators when the "bad actor" is the author and vice versa.
I get it that 'free DVs' had their place in the past. I am not convinced, at all, that they represent the best solution moving forward. It represents a small-minded solution (imho).
As long as social rewards exists on layer 1, it is necessary.
Until the day ALL social rewards cease to exist on the base layer, your idea only punishes good actors.
A robust second layer is the only way your idea can be viable.