What's interesting to me is that there are a handful of languages that include gui frameworks: tcl with tk, erlang binds wxwidgets, and racket has its own thing built on gtk.

It's curious what these languages have in common too: as languages almost nothing. But they're all venerable, proven & respected in their domains if not beloved, and relatively unpopular.

I don't know how to interpret that. Maybe it's just a coincidence. Or stdlib gui frameworks are just out of style and it's survivorship from the old ones. But then python is from around the same time, why doesn't it?