I'm wondering whether the ability to downvote questions in the currently implemented way is the best way to handle bad questions. I'm ignoring meta sites for this, as they're far more complicated and voting works differently there.
The benefit of downvoting answers is very obvious to me, if an answer is wrong or simply not a good answer, downvoting it pushes it to the bottom and lets better answers rise above it. For questions it is not as obvious to me, especially as it's far more nebulous what actually defines a bad answer. For questions there is also a parallel quality control mechanism in close votes. And downvoting questions doesn't let better questions rise to the top in the same way it works for answers, it doesn't do anything for question lists or specific tag views, only for the frontpage.
One important aspect of downvotes is that they feed certain automated mechanisms designed to reduce moderator burden and clean up the site, the automatic question bans/throttling and the automated deletion of questions after a certain time.
One drawback of the current way downvoting works is that it is often perceived as very hostile, probably to a largely irrational degree. Even as an experienced SE user I still get a bit frustrated when I receive downvotes that I don't consider justified. And this effect is certainly much worse for newer users. I don't want to open this specific discussion here, but the perceived hostility is a significant issue in my opinion because it likely reduces the number of new users starting to participate, and a steady stream of new active users is necessary to sustain an SE site.
In my subjective observation there is also plenty of spurious voting on posts that are not actually bad. There is no general agreement on several aspects that people consider to make a question a bad question. A single downvote doesn't mean anything, there is too much noise in downvotes to gain any information from it.
Another issue I have with the current downvote mechanism is that there's often an excessive amount of downvotes for really not that terrible questions. The amount of downvotes is driven by attention (just like upvotes), and it often feels like kicking a user again when they're already down when you drive their question far into the negative score.
To me, closing is the primary way of moderating questions. Downvoting questions feels like an inferior parallel moderation system to me. The advantage of closing is that it actually explains to the user what is wrong with their question and gives them a chance to fix it, even though few take it. Downvotes don't tell you what is wrong.
The negative reputation penalty of downvotes also doesn't serve any useful purpose in my opinion. It's too small to have a serious effect on people that ask crappy questions, and it's large enough to simply annoy people.
What would happen if we remove the ability to downvote questions entirely? The question ban and the automated deletion script would likely not work well anymore. I'm not sure the experience for answerers would substantially change. The frontpage would also show questions that would have been below -4 score previously, and the worst possible score would be 0 for any question, so you would not quickly distinguish questions with no feedback from questions with negative feedback (but still unclosed). The asker would receive less feedback that their question might be bad, but only in cases where people don't post that feedback as comments and also don't close the question.
If we assume that community moderation in terms of closing questions works well, I don't see many drawbacks in eliminating downvotes on questions. This is a rather big "if", but maybe more an argument for improving the close system than having a lesser, parallel moderation system in downvotes.
Do we actually need downvotes on questions, or are they a superfluous parallel moderation system alongside close votes?