At the risk of igniting a flame war (and/or downvotes without discussion about how to take an idea and make it better to solve the problem) about removing anonymous, uncommented downvotes...
Make downvotes a separate item, either as a section or in-line with comments (which would preserve the time-order). Make them attributable to the downvoter and require a comment of a given length.
Then provide people the ability to concur the downvote. The downvote and the concurrences would count as the existing downvote count. This might still allow anonymous downvoting via concurrences, but the problem is identified, can be responded to, and can later be marked as fixed, eliminating the downvote cast.
Likely, marking a downvote fixed would require a certain reputation. This would also allow one person to sweepingly remove someone else's downvote and all concurrences.
This has many upsides. Perhaps some newbie garners several downvotes with concurrences causing a substantial downvote count. Before they even check this, reviewers fix some of the original downvotes. They return to find the corrections in place and only the now appropriate remaining downvotes. They fix them. Someone acknowledges this and marks the downvotes fixed. Now the voting is where it is now appropriate to the current state.
If a downvote states a reason, such as, "Poster did not research subject," when someone notes that research has been done, why shouldn't they be able to reflect that? The objective is good questions and good answers. This allows a policy where people can edit other people's posts. If my post isn't exclusively locked to me, why should a criticism (which should be appropriate) that has been appropriately addressed?
Right now, if you have the reputation you can downvote anything you don't like without comment or attribution. This is considered by many to be a virtue. It is not at all. There is no debate. There is no discussion. There is no appeal. There is no ability to fix. And the reason need not be supported by the rules. If you don't like it, that is good enough to downvote -- no one will know.
The poster's question is about asking someone to revisit their downvote. If they don't want to, no amount of tweaking this system to "help" will change that. So I propose that the community should be able to address it. The first response is, "They can, by upvoting." But that is false. Upvotes are for "good", not "problem fixed." These are not at all the same thing. You should not vote "good" for "fixed."
As to the same issue with upvoting... I have no problem at all requiring attribution and comments to upvotes. People won't like that it takes longer. Sure a popup with pick your reason including "I want to know the answer" or "Very well prepared" or a field to free type would be fine by me.
But, this eliminates the free fire-and-forget anonymous, uncommented downvote...
@downvoter, as I see sometimes) which the downvoter would then see, would be nice.