[ColinWright]

People do down-vote anything they disagree with, and there's nothing that can stop that. You can't change people's behavior.

However, removing the ability to down-vote won't really change anything in this regard, except that it will stop people from feeling attacked when they get a down-vote. What would change is that there would be no feedback about genuinely inappropriate comments, and I think that would be bad.

The only thing I can think of is to separate "down-vote" (meaning "of little value") from "inappropriate", label them clearly as such, and have the consequences of a "down-vote" less apparent and less severe. Then you can only trust that the behavior will sort itself as the "community" decides on the meaning of "inappropriate" and "of little value."

[JoachimSchipper]

I think the "canonical" solution is changing the audience by migrating to a new site...

[ColinWright]

That may yet happen/be happening.