Well I have been using haskell and clojure in vim for a few months now, but since most haskellers and lispers use emacs, I figured there must be a reason.
I would guess that's for other reasons. I often associate Haskell and Lisp with academics, and emacs with a slightly older crowd, and there is some over lap there. Of course, I don't think they should be strictly limited to these crowds, this is just a guess based off personal observation.