Coming from an art background and being an artist myself, I honestly roll my eyes at no use of color books. Plain and simple: it helps with fine motor skills. My DD colors when we are out and about, usually at restaurants. She also draws and writes and I have yet to see her creativity stifled by such acts.
As for over use in school ... I see this as a problem and it is part of the issue of repetition in general. Teachers rely on coloring books/pages because they can't seem to think outside of the box.
I do have a problem when teachers roll their eyes at a child's drawing and consider it scribble when clearly there is something there of imagination and creativity. I've witnessed this first hand and it set me off as I listened to the teacher put this little girl's work down because she refused to stay in between the lines as she colored. But, to jump to absolutely NO coloring books allowed ... it's just as extreme as constant assignments of coloring.
