Elm is still somewhat "experimental" and the popular opinion is that Elm is nothing but a paved road to Purescript - which in turn has it's own steep learning curve. Also FFI to Javascript in Elm, Purescript, Fay or GHCJS isn't as smooth as it's with Clojurescript. Sharing code between back-end written in Clojure and front-end written in Clojurscript is a real thing and not some kind of myth. "Cleaner and easier to understand syntax" is very debatable, seasoned Lispers won't trade the power of symbolic expressions for anything else, because nothing is more cleaner, concise and readable than the code expressed in its pure, unambiguous form.