I think there are benefits to being able to see downvotes. By looking at the posts & comments of someone who downvoted something, you can come up with an idea of why. Additionally, it can make people think more before handing out a downvote — if you know that people can check that it was you who downvoted, you're more likely to consider whether you can actually justify your downvote.

But of course, someone could go harassing people who downvote them (e.g., in DMs), and that possibility can make people less likely to downvote at all. I think that with a good block feature, harassment from downvotes won't be that big an issue, but there's definitely good reason to hide who downvoted something. I don't strongly lean either way.

(And as a side note, I really like being able to see who upvoted something as well. It's just neat info to know tbh, especially in smaller communities.)