I don't have any interest in using the subpar terminals/"execute this thing" buttons included in many editors. I'd rather use a terminal that I actually like -- the one I use for everything else.
I also don't want any "magic" to happen under the hood to run a thing (looking at you, Java IDEs). I want anyone to be able to download the thing I'm working on and run it without being tied to a particular editor/IDE, and the best way to do that is to put your build/run stuff into something portable (shell script, Makefile, task file, whatever) instead of relying on a button in a GUI somewhere.
For me as well. However language specific IDEs these days usually don't have much if anything on more popular editors.
Edit: And that said, if I'm paying money for a product it better have features that I'm going to need, and if I don't need them it better have a way to disable them.
Ideally, I'd love a way to glue sets of windows together and move them around as one piece, without being a tiling window manager.
I'm quite happy with my current editor and probably wouldn't use this, but I have also never used either of those features. I run my code using a separate terminal in a separate window, and can't really understand why anyone likes squashing their terminal into the same space as their code (although I recognise that they do, and I'm glad that they can if that's what they want) - seems like it would be distracting and reduce the amount of code you can get on screen at once.