While I would not say that Elisp is the greatest programming language every created, I would hardly call it horrible, nor would I call it entrenched in the past. The Emacs designers seem to put real effort into improving the language over time, even to the degree of breaking backwards compatibility. That's pretty hard to for an editor that greatly depends on the functionality of user-written extensions. Also, consider the recent addition of lexical scoping. That's a brobdingnagian change to a programming language, editing language or not.