If I remember it right, Lumo and Planck (mainly) were created to deal with the long startup times of Clojure. People needed a faster way to get the REPL up and also something that can run tiny scripts. With the emergence of Graal, and tools like babashka, it looks like the JVM warmup time is no longer that big of a problem.

I just saw the original developer is now focusing on a fork of ocaml's bucklescript so I'm not sure how much more work it's going to have.