I don't remember everything on top of my head unfortunately, but it was things like, weird choices all around like long names, no real OS threads, that kind of stuff. Sorry, I don't remember, I just know I tried it a couple of times and disliked it.
I have to agree on you regarding OS threads, although there are places, but they're processes.
For long names, most names have an abbreviation like call-with-current-continuation has call/cc, and in any case, you can make your own abbreviation using make-rename-transformer so this shouldn't be an issue
Why would one bother when clojure has core.async, short names and everything else?
Because racket has hygienic macros and #lang, and syntax-parse.
The tooling is complicated with Clojure. If you are teaching an introductory class, having a single simple install of DrRacket is a big plus.
Good point. Though I'm not so sure it's such a big deal in comparison of using a language that's not entertaining.