On MSE, down voting means I disagree, not "bad post." IMO, we don't want to punish users for writing potentially controversial ideas, so there should be no penalty for being downvoted. The other metas are already like this.
I think the current voting and reputation system does a good job of gauging community consensus on issues.
Even potentially controversial ideas can usually be written in a neutral way that simply introduces the issue and leaves answers from others (or you) to attract up/down votes on the for/against cases as appropriate.