> Lack of access to the C libraries.
???
I recently started learning Common Lisp for fun (and fun it is!) and the ease of accessing C libraries was one of the things that surprised me in a positive way.
Using https://github.com/rpav/cl-autowrap one can simply write (c-include "file.h") and the API defined in "file.h" is accessible from Lisp. I can't think of a simpler way.
Even without cl-autowrap, FFI using https://cffi.common-lisp.dev/ seems simple enough.