I agree; with vim as well, gVim isn't much help to those who still want to use a mouse / don't know the keybindings. Atom is really the most versatile open-source GUI text editor right now IMO.
But they didn't, my guess is because NIH.
Perhaps but nobody has done it yet.
Emacs and Vim are like Lisp at this point: unicorns. Perfect, mythical creatures everybody loves to talk about. Meanwhile oxen like Eclipse, Visual Studio, Sublime, etc. keep chugging 90% of the world's code :)
I've been waiting for this for literally a decade with emacs. It hasn't happened and I don't have the expertise to do it, so nowadays I exclusively use IntelliJ for the languages I can. I'm probably going to start using CLion with it as well.
There are lots of aspects of Emacs that I miss but I hope that IntelliJ can take them over with future iterations of the vestigial "IDE scripting console". They just need to put a lispy language in there like Clojure and bindings into the editor like Emacs Lisp has.