There are plenty of Vim emulator plugins for "GUI editors" like Atom (or even the Visual Studio family, as a comment in this thread mentions) that do just that!
It would be great to be able to use VIM key movement as drop-in replacement for any text field OS wide but the VIM interface (the command line) plays an important role in the UI and I don't see how it could be swept aside without losing some VIM core functionality: EG how do you :%s///gi without the overlay command line ?