With regards to lexical scope, yes elisp has that now, but it didn't for so long that a ton of existing code, including the standard library and editor interfaces was written without it, and there is a TON of global state.
And that's usually good, because the whole point of Emacs is to make it easy to inspect and manipulate it. It's one case where information hiding and encapsulation - including lexical scope - get annoying very quickly.
It would probably require a lot more thought about how to make things so modifiable, yet avoid the global mutable state. Yet I think that is the work that will need to be done sooner or later, step by step, to keep the platform relevant.
