I'll also feel it's about time the Emacs Lisp standard library got a bit of facelift. In a time when most Lisp have embraces `first` and `rest` where're still clinging to functions named `car` and `cdr` for instance. Sure, lib-cl has `cl-first` and `cl-rest`, but I can't see the harm in having those aliases in the "standard" lib.
dash.el and s.el show can be used if not directly at least as a source of inspiration for modernizing a bit the list and string manipulation portions of the library. We don't even have in built-in equivalents of `filter`, `select`, etc. I guess most of you have noticed that most non-trivial Emacs Lisp packages starting with `require 'cl` (or more recently `require 'cl-lib`). This speaks volumes of the limitations that developers are facing with the current standard lib. We don't need ANSI, a committee or lots of money to make the library better - so why don't we? :-)