I think dynamic functional programming languages such as Clojure are great for "creative coding" because they go straight to the point. You don't have to instantiate complicated objects, create classes all over the place, or consider every single code path to make the type checker happy. An advantage they have over non-functional (or "less functional") scripting languages such as Python or Javascript is the ability to move code easily without breaking anything (because most functions are pure).

Processing would make a good case that it is dynamic languages that help moreso than functional. Specifically, dynamic in that you can interact with a running program easily.

This really does get into a lot of the power of many lisp setups. It is not so much that there is a REPL. There is a nice ready made hook into a running system.