Even if gedit looks simple, it’s actually a lot of work to develop a good text editor. You can take a look at the number of lines of code, for example. And there is a whole library stack beneath.
gedit is not changing directions, it’s a text editor, not an IDE. Things like compiling and running the code, doing git commits, running a debugger, looking at the documentation etc etc are done with other apps, often with the terminal.
And each time that I do something more advanced with GTK, I wish it was with GTK 3.99/4 because I know the APIs are nicer to use with GTK 4. So, porting to GTK 4 is yet another item that I would like to tackle, but it doesn’t materialize out of thin air, it requires work.
See also this reddit thread where I’ve answered other questions, or this older reddit thread. So yes, a lot of people appreciate gedit and use it for various purposes (not just for writing quick notes).