Good write up and I agree with your points. At the same time, I think downvotes are a difficult issue. Hear me out—I'm going to ramble a bit (but hopefully there will be a point in here somewhere)
This is a logical vs emotional thing. On one hand we can all understand that downvotes are not necessarily personal and only express some kind of disagreement: with a point you made, with the reward size, with something else. But on the other hand, it feels like a personal attack. And that feeling is not only hard to ignore, but hard not to respond emotionally to.
We see this problem a lot in writing critiques. Back when the Writers Block was a thing on Steemit (I think they self-destructed long before Hive) I was a poetry editor there. And before that, I took many creative writing classes at Uni long years ago and I remember the problems of critiques. The thing is, no matter how nice you are in your critique, no matter how softly you try to pad things, people get really really hurt, to the point of bursting into tears, running away, quitting. Now objectively that seems nuts. Why get so upset over someone pointing out that you have a tendency to use run-on sentences, don't know how to use a comma, or tend to have characters speak when you should be having them act? But trying to look at it from their side, they worked really hard on their story or poem or writing, they put a lot of energy into it; not only that, but they allowed themselves to fantasize when writing it about how successful it will be and how much praise it would get. Getting any critique after that is like a slap in the face.
Again, objectively that is silly, but we do need to understand that is what's happening. I mean it's human nature. We can say it shouldn't be this way, but we can't (or shouldn't) deny what it is.
I have been on the other end of this too. Sometimes I submit my poetry to publications. Like almost all writers except those who have made a name (eg Stephen King) I am rejected more than accepted, and those rejections still always hurt a little. I can say thank you, I understand, and I can take any points given to heart, but I still don't feel good about the rejection. I've writer friends who are in advanced age and they tell me they still have the same reaction.
Downvotes trigger the exact same emotional reaction in most people.
Let's not mention that when you get a downvote, it's what, 1 or 2 out of the 163 this post has made. You can shrug and move on. But when a newbie who only makes .1 on a post they worked really hard on, then someone comes along and downvotes it to zero, that really really hurts. Even if the downvoter leaves a comment "It's not personal, I just don't like the point you made", that still really hurts.
Hmmm
So I don't know. I mean I agree with what you write and I think we do need to police the system to encourage more high quality posting and less trash, only-for-a-voting-trail-vote, posts. But at the same time we have to be careful with downvotes because they can also be very hurtful and disincentivizing. Hive has enough problems attractive new users, we really want to be careful about not chasing the good ones away.