Hi @ats-david, I'll try to address this point-by-point and hopefully clear some things up.

I don't understand the need to "counter" downvotes that are cast by other users because they were cast based on an "opinion" (which is unknown, unless explicitly stated).

That's just it; people sometimes use a DV as a substitute for challenging an idea or opinion. This usually takes away any chance for meaningful engagement, and instead escalates things with negative interaction. If the very tool that is used to punish spammers, scammers, and plagiarists is also used to disagree with something, then not only is it a big "fuck you" to the person who was DVed, it also reverberates through to the little guys that are still trying to figure out their future on steemit.

It sounds like you want to counter a downvote that's based on subjective opinion by casting an upvote that's based on subjective opinion...and often just an assumption about motives.

The intent is to leave opinion of the post out of it, and basically judge whether it's a job for steemcleaners, or if it's something like tag abuse etc. The subjective opinion to DV a post is equally as valid as the UV that I may follow it with. And maybe, just maybe, the user will choose to leave his thoughts instead of a DV next time so nobody will have to assume, and discussion can begin.

Why is there no desire to counter opinion upvotes?
Why are upvotes made with "questionable motives" not scrutinized or vilified like downvotes?

UV reward nullification is a whole other topic, and one that other users like @smackdown.kitty are addressing. One of the main points of this place is the ability to be rewarded for making original content. Making the judgement call on what rewards to remove will have the strongest impact, and I think many are underestimating the ramifications of that.

Do you think that a service is really necessary to hunt down and counter only one type of vote, and do you think there can be negative consequences from this that might end up being worse than people receiving downvotes?

I do think that this service is necessary, and a glance around the comments here will show there are many others who agree. I do know exactly what I'm risking by doing this, and if someone were to obliterate my account for running this service, then I would take what I learn from that and move on accordingly.

I guess you could consider this my bellwether test to see if my future lies on steemit. My little vote isn't going to be anything significant without others chipping in, whether that's following resteems and UVing or delegating SP to the account. I want to know if the community thinks free speech is important enough, and also if this place is resilient enough against big moneyed interests using their swarm of bot accounts to control a narrative in the not too distant future.

As for you last question, I simply do not know. I can only do what I feel is necessary and see if the community support is enough to continue the effort.