I think immutability plays a big role here as well. Clojure makes it natural to structure your code in a way where things can be reloaded individually without having to worry about global state. The REPL would be of much more limited use in a language where everything is coupled via shared mutable references.

This can also be seen with ClojureScript where hot loading works reliably out of the box, while all attempts at do hot loading in Js are flaky to the point of not being of much use.