I'm in a similar boat as in the first quote: Have used emacs for decades, glad that I do, can't imagine switching... don't think I would recommend it to anyone new, unless they are really open about learning something entirely different. Emacs seems to be in the same position as LaTeX: Outdated paradigms that would probably need an entire redesign from the ground up to start "making sense" in the modern world. This s…
Why redo something if it works? People are still using Fortran because it works well for certain applications. Just because its old doesn't mean its outdated. I could even argue that since Emacs hasn't been phased out (and still has a decent user base) that it does something that other text editors don't (or can't) do.
In particular, the biggest change I'm aware of with Emacs Lisp (the language) is that we now have lexically scoped variables. The biggest change to its implementation has been a push towards native compilation (much improved performance, I like it). The language has, otherwise, largely remained the same.
In some regard, this can be seen as a consequence of having a decent base language. Where Fortran's original version became increasingly indecent as time went on, Emacs Lisp seems to have held up better thanks to a stronger foundation. That doesn't mean there isn't room for improvement.
In particular, the things that (my opinion) are still missing from the language are:
1. A good concurrency model. CSP, actors, I don't care but it needs to exist. Paired with the native execution we're getting now, this would greatly improve the real and perceived performance of the system.
2. A real module system. I'm not talking about a package manager, but moving things into module scopes a la Common Lisp packages. The prefixed names for functions and variables is a hazard. Even if you leave every symbol exported by default so that you don't lose visibility to module internals it would be better than now. It would also open up a lot of opportunities like the potential to run multiple versions of the same package side-by-side.