I think you should ban people who never down-vote. I always go into questions that suck, only to see comments from people saying "This is a terrible question, please rephrase it". Why don't they down-vote the question then? Scared to lose one point, you silly user? I would not waste my time with the question if I saw it was at -1! This bothers me.
Banning might be a bit harsh, but... This is a problem.
Keep in mind though, there's a bigger problem: sympathy votes. The user who posted that comment may well have down-voted the question, only for it to have been up-voted again by some misguided busybody who felt sorry for it.
There have been a few proposed solutions to this, but ultimately it's a social problem: most folks just aren't critical enough.
- Comment and give people a chance to fix things unless the transgression is really egregious;
- Downvoting people on 1 rep is a pointless activity;
- It takes 5 downvotes to counter 1 upvote. Questions and answers on less than 0 net votes are much more likely to attract "pity upvotes" cancelling out the effect; and
- Downvotes received can be cancelled out by subsequent upvotes (up to the daily rep cap) meaning that if you answer a lot of questions you can largely ignore downvotes anyway, so there's even less reason to downvote such a person's posts.
It would be interesting to separate out downvotes on CW posts (which cost the voter nothing) out of people's upvote/downvote stats to see how many "real" downvotes people actually hand out. I imagine not many.
The reason I am hesitant to down-vote now is that it's harder to take it back. I used to down-vote poor questions/answers early and then undo after it had been edited. Lately it's been harder (for me anyway, also that's what she said) to time it correctly to avoid the "This vote is too old to undo" message.
Closing questions and flagging for deletion those that are irretrievably broken is immeasurably better than downvoting in my opinion. Downvoting can result in self-deletion, but only if the OP actually cares or has rep to lose. Most often poor questions come from new users who have none and probably are unaware they can delete their question anyway. I choose the more effective mechanism for completely broken questions.
Questions that can be improved should be by those who can edit. If you have enough rep, rather than downvote or complain via comments, why not repair the question and make it useful. The OP benefits because now he/she may actually get some usable answers. The site benefits because it has one more usable question.
I usually reserve my downvotes for bad behavior -- consistently posting poor questions, trolling, and the like. In that case I'll often downvote and flag, getting a 2 for 1. Even though the rep cost to the OP is relatively low it sends a message about the behavior that it won't be tolerated (at least by me).
I down-vote a lot :)
I just did a quick experiment - randomly clicked 10 user names who had more than 500 points. 2 of them had not a single down-vote, 8 of them did. Of those 8, the average number of down-votes was around 15% of their up-votes, which seems quite reasonable.
I think your suggestion is too drastic, banning people just for never down-voting. It's a fine balance to encourage people to down-vote but make it hard to abuse. The -1 is necessary, but if only 20% of the people never down-vote that's probably not too bad.
(obviously my stats are really, really crude)
Are you claiming that you don't even read questions that are at -1? How does a question being at -1 affect your ability to answer it correctly and get upvotes?
Yes, I know this isn't an answer. It's a comment, but I want to separate the discussion of this from the discussion of the question itself. If it's abuse of the system, then so be it.
I don't down vote unless it is really horrible question. like suggesting to ban people who doesn't down vote? jk I don't think up vote and down vote are the purpose of SO, it maybe the purpose of less quality sites like Yahoo Answers. but here it should be a useful tool for users who want to use it and help. I see many questions down voted recently, but they are good questions and clear. it is possible the one who down voted such questions didn't understand it . beside users new to the site may need help you explain to them the issue and give them chance to modify their question.