What is the justification for having downvotes and not just close votes - on questions?
How can a question that fits within the remit of the site, have -ve value?
I'm not being facetious, I just don't get it.
a heavily down-voted question or answer is not worth the time to read, while one with up-votes might well be worth a look
Despite the triviality of this answer, it does show how downvotes on questions are a means for the site to quickly assess a question's worth to its users. Without downvotes, only questions asked at the same time can be ranked in terms of how good they are, if they should be read and answered.
But don't most people use the site in that way - looking at new questions?
But I do feel that the downsides of doing so might on some subsites (a culture of recrimination, unhelpfulness, etc.) outweigh that positive.
At a minimum, if people can downvote questions there shouldn't be such a stigma attached to questions that are poorly received - at least ones that make sense, are on the right board, etc. (all closable offenses). IMO, though of course you're welcome to disagree.
Close votes don't affect a user's reputation. There needs to be some stimulus to not post all rubbish you can think of.
Downvotes on questions are meant for unclear questions, or questions that don't show enough research effort. I think it's reasonable to get a downvote in such cases.
Also, I don't see what problem not having downvotes would solve.