I've always enjoyed PHP, but never really enjoyed Javascript until I started using jQuery. I continue to enjoy using jQuery much more than vanilla Javascript. Using jQuery has not always been about filling in a gap of Javascript so much as it has been about preferring and even enjoying the interface. It’s fun to use, and Vanilla JS not as much, at least to me. PW has some of its API inspired by jQuery, and together they have always felt just right. When it comes to open source stuff, I like to focus on tools that I enjoy using, as that's what keeps me interested and keeps me going. If we were to take jQuery out of the admin, it would be a huge amount of work, and then leave something that would be less interesting to maintain. So I’m not so enthusiastic about taking jQuery out of the admin.
Where I would be enthusiastic about it is with front-end modules that might currently be using on jQuery and don’t necessarily need to. Take FormBuilder and LoginRegisterPro as examples (though there are many more). Perhaps those modules don’t need to require jQuery unless one of the Inputfield modules in use requires it. That way, modules like that aren’t introducing jQuery in an environment where it might not otherwise be in use. And maybe there are some Inputfield modules that currently use jQuery and don't need to. Since Inputfield modules can be either admin or front-end, it makes sense to use vanilla JS when possible with those. So yes, I'm all for reducing or removing the use of jQuery in spots, but not so interested in removing it from the admin.