I guess because I fall into the first category. I use the same text editor for a wide spectrum of languages that I fiddle with, and feel like the time spent by core language devs on an IDE is better spent on the language itself.
People who work on IDEs / text editors can work on tooling and integrating with languages as they become popular (or before), but developing an IDE from scratch with a language and continuing to support it seems like a waste of time when I personally would never really consider using it and its chances of being a decent text editor are slim.
Which is all not to say that I definitely do like coordination between the two camps.
So I guess I made two arguments, one that I like what I use and prefer to keep using it over having some new perhaps questionable tool, and two that it's a non-trivial amount of work that has already been done, which I feel is better spent by other external parties rather than core devs.
The PL designer can always customize an editor off the shelf (e.g., Eclipse), and this is what happens mostly. However, I find myself implementing an editor now simply because the idea I want to show off requires many features current editors don't support, like projecting code onto program execution rather than have separate windows for code and inspecting run-time state.
People who work on IDEs / text editors can work on tooling and integrating with languages as they become popular (or before), but developing an IDE from scratch with a language and continuing to support it seems like a waste of time when I personally would never really consider using it and its chances of being a decent text editor are slim.
Which is all not to say that I definitely do like coordination between the two camps.
So I guess I made two arguments, one that I like what I use and prefer to keep using it over having some new perhaps questionable tool, and two that it's a non-trivial amount of work that has already been done, which I feel is better spent by other external parties rather than core devs.