Elisp is a really poor language compared to almost anything else, more work should be done to allow Emacs to be configured in other languages.
What makes Elisp a "poor language" in your opinion?
Elisp is actually a really good language. Especially compared to other languages used for scripting, like Lua or JS. In some areas Elisp is significantly more advanced than either: pattern matching (pcase, dash), object orientation (multimethods, multiple inheritance), iteration (loop), data types (Lua has 3, JS a bit more, while Elisp gives you lists (pairs, proplists, assoc lists, trees), vectors, maps, unicode strings with optional metadata, queues, rings, and more. While the lack of reader macros is unfortunate, the macro system along with hooks and advice allow for writing libraries that integrate seamlessly into the environment, and ones that cleanly hide a lot of complexity (ie. use-package). Additionally, Elisp performance is not very bad (though of course worse than JITed languages) and it got AOT native compiler recently, which should help improve upon it.
Namespaces are the only lacking feature at this point. I mean, there are lots of places where Elisp could and should be improved, but it's in quite good shape already. Definitely not "really poor", especially compared to the other scripting languages.
What language would you re-write Emacs configurations in?
I don't remember what the core to elisp fraction is, but it's not that big.
-----ADDED-----
Emacs Lisp: 1,171,507
C : 318,611
C Headers : 43,738
That's a lot of code to replace, and again, just what's in the core distribution.