This is exactly what I have been thinking lately, starting with looking at Oberon. It seems to me that writing a simple GUI should be the same as writing a simple text-oriented script. GUIs have their own challenges, of course. However, doing the GUI equivalent of print() statements to show calculation output is a think a modern operating system should do, not have a distance between user and the graphic system. At the moment, it's a pretty ideal, but there are cases I wish their was less friction with it.

edit: I never tried, but isn't this where Smalltalk comes in?