I'm personally willing to give SSH a partial pass because I feel like having it separate makes it easier to reason about from a security perspective (this would also apply to GPG).

For vim... yeah, AFAIK "vim" does that, but neovim uses ~/.config/nvim :)

And to your general point... yes, many of these programs predate XDG. I happily support keeping them backwards compatible (which should be easy; checking multiple places in order is a time-honored tradition). But I honestly don't think this was a good idea even decades ago, and "we've always done it this way" is a terrible reason to not even support a newer, cleaner approach. Again, there's no reason to break existing systems; just support an additional location, probably make it the default, and everyone will be happy.