It's not that languages like Racket, Rust, Haskell or even something like Prolog and other languages aren't interesting or useful, in many cases they're a better fit for your problems. It's just that without the background in the C-style and object oriented languages it's pretty hard to appreciate the more "niche" language and the problems they solve.
I have seen developers complain they had to learn an unpractical "ivory tower" language like Haskell - and then the same developers get totally lost when C# introduced type inference and closures and deferred evaluation of queries.
Between Go Rust, F#,Nim, Kotlin etc I think ML-style syntax, and composition over inheritance is generally being preferred in a lot of newer up and coming languages. As well languages like C#/Java/Rust are so multi-paradigm these days the crossover relevance is very high from any one language to another.
I've never seen most languages as drastically different really. Lisps and Prolog certainly are, Rust is a little with the borrow checker, but otherwise I feel like people make much ado about "int x" vs "x :int" and "f(thing)" vs "thing.f()"
Did these students have prior programming experience? Was their reaction due to a particular fault of Racket or would they have disliked any language to which they were not accustomed? Perhaps their reaction was to the idea of functional programming which would have provided a distressing challenge to intuitions developed through object-oriented or imperative programming? What textbook did you use?