I guess being able to see a whole bunch of things at the same time is useful, plus never having learn much SQL, plus being edit things by clicking on them.
@antihero : Seeing things does help, but in my experience, using scripts and the command line is faster for developpement, because a lot of code can be reused, which is not the case with clicks.
I was being too restrictive though, a lot can be done with a GUI, of course.