So I agree in part with your point that emacs doesn't really need to change their UI/UX (new menu, new shortcuts, etc). The Emacs model takes time to learn and is different from the rest of the world, but it works quite well once you take the time to learn it. That's not for everybody, not necessarily beginner friendly, but that's fine, emacs is a quite advanced editor environment, it has its own niche of users.

But some things make emacs just a bad editor, even for people who did spend the time to learn it. For example emacs is horrible at dealing with big files. The entire editor is stuck for seconds if you open a log file with just a few megabytes of content. Emacs performances are also really bad when compared to other editors, simple syntax highlighting or intellisense is just really, really slow.

I used emacs for years as my main editor because I was happy to have something stable, because I love lisp, and because I really like the introspection and control you get. But at some point I realized how fast and way more advanced other editors were in comparison to what I could get with a tuned emacs environment and jumped ship.

Even keeping the emacs UI and UX there is a lot of modernization that can be done under the hood to make it up to the task of the modern world.