1. A few other libraries still depend on jQuery in turn, so I find that I still usually have it available in every app I work on anyway, so I might as well use it.
2. It "just works" and I already know it, and since it's already there, anyway (see (1) above) it just makes sense to use it. IOW, I don't feel enough pain from using jQuery to justify going off and learning what combination of new ecmascript (es6? es7? es9037253223252??? ???) features and/or libraries du jour that I would need to do everything jQuery does for me now.
That said, I mostly just use it for the selectors - which I understand can be easily replaced with native features now - and the ajax method. So in reality, yeah, I probably could ditch jQuery without too much pain, excepting for (1) above, but... why bother? I don't care too much about the size, since I don't typically link in tons of javascript libraries, ad networks, etc. to kill page load times, and page bloat seems to be the biggest argument I hear against using jQuery.