I'm not criticizing the power of TeX in terms of typesetting, I'm only referring to the _language_ here. (And you are aboslutely right, Org and other markup languages are not competing with TeX.)

Imaging the capabilities of TeX with a good programming language.

I don't find WEB beautiful. In my opinion, literate programming (at least in this case) is a pretext to hide a terrible, unexpressive programming language.

As you're saying, Emacs had the good taste to use a Lisp back in those days, so it really is a pity that TeX didn't.