Disclaimer: I've read Should downvotes on questions be "free"?, but I feel the landscape has changed in the last three years. What I'm looking for here is discussion about the results, looking back. I've included the best stats I could find, but if you have better numbers, please share.
Downvotes on questions are "free", while for answers it "costs" -1 rep. Making the question votes free was done, according to the linked post above, to encourage voting on questions, and as a way to filter the good content from the bad. These are fine ideas, but a few years later, I'm not sure it makes so much sense.
First, some numbers. I'm keeping this focused on Stack Overflow because that's where I'm most active, and I suspect smaller sites may not have the same issues.
U/D Ratio 11.291
U/D Ratio 33.081
We can all see that answers are still voted on more than questions, but this (IMO) is natural. What we can also see, though, is that questions are much more heavily downvoted than answers. If you post a question to SO, you have a 1/6 chance of being downvoted, while answers have a rate of 1/15.
Are the questions really that bad? Many would say they are, and this is natural. However, these numbers don't take into account deleted questions. Many "bad" questions are voted down, put on hold, then closed, then deleted. The deletion script in particular specifically looks for downvoted/closed questions to remove them. I feel that if we got the numbers including deletions, it would skew it even more.
Next, look at the Up/Down ratios. Back before question downvotes were free, the ratios were surprisingly even. Both questions and answers had a ratio of about 20:1. Now, questions are at 11:1 and answers are at 33:1. I believe this is direct result of one being free while the other costs rep, and I don't believe this is a change for the better.
In addition to everything so far, we have better tools to get rid of bad questions, and are lacking on answers. You can't put an answer on hold, you can only flag, downvote, delete. Many answers don't fall afoul of the flags, but are still bad. The only recourse here is to downvote, yet it's the only thing on the entire site that costs rep to do. Okay, bounties cost rep, too, but it's the only moderation-like tool that costs rep.
Another relevant topic is "piling on" downvotes, especially for new askers. Often a user wanders in, asks a not-quite-good question, and within ten minutes is staring at a -5 or lower score. Why? Because downvotes on questions are free. Yes, you see answers get downvoted quickly, but almost never as fast or as far. Why? Because they cost rep. Many users feel we should be more "friendly" to new users. I'm not sure where I sit on that, but I feel that in general, the "right" option is to put a question on hold, not downvote it into oblivion. The current system seems to encourage the latter.
Overall, I guess my question boils down to: Does it still make sense for question downvotes to be free?
After restricting this to only the past year, the current ratios for upvotes to downvotes are 3.6:1 for questions and 27:1 for answers. This means the disparity between question/answer voting is wider than I initially thought.