Some const features seem like big anti-patterns though. One example is the unstable feature `generic_const_exprs` which I think is a bit short-sighted.

What seems short-sighted about that to you? I'm not super familiar, but it seems like something you'd want if you're using const generics.

"In progress" does not (by itself anyway) contradict "less-loved". Something can be in progress but making slower progress than it would if people were really excited about it.