Earlier quoted context omitted.
In Emacs 31 none of what you’re saying is true. Grammars auto install and setting them up is easy. https://www.reddit.com/r/emacs/comments/1utghab/treesitter_s...
Well that's a nice change; I'm still on Emacs 30. But note that this is not the default. Users have to enable that behaviour, and know to enable it. That's a bad default.
IIRC, for eglot I had to install a Python language server. There are a bunch of them. Why would I want it to pick one by default?
I don't know if Emacs will ever have an IDE with TS and LSP working "out of the box" without some configuration. From my experience with Eglot, if it were enabled by default, it would confuse the heck out of some users who just want to, say, edit a Python script.
There are always opinionated releases like Doom Emacs or Spacemacs that can set whatever nice defaults you think should be there. Leave vanilla Emacs to be, well, vanilla. Emacs, while it can be a decent IDE, is not an IDE and shouldn't default to being one.