Why do we feel that a downvote is such a big deal? A downvote doesn't mean "we think your an idiot, go jump off a bridge or at least don't ever post here again". It means that this comment isn't up to our standards, and you should do better next time.

It's a big deal if it's the first or only vote on a comment, because it puts the comment into the negative. A negative score by itself presents the message, "the community considers your contribution a net negative".

I suspect, though, that if the same score were displayed as "+0/-1", it would communicate a VERY different message, i.e., "One person didn't like this, and nobody else cared one way or another."

Those two messages are likely to produce different effects in most people's brains.

If I understand correctly, the distinction between not voting, upvoting, and downvoting is too broad. A -.3 vote would give a fourth option that allows for "Didn't suck, but not great."