Here's an interesting article on the need for polarization in art photography:
http://www.betterlight.com/downloads/conference10_speakers/guyer_Polar ization.pdf
I've found cross-polarization (i.e. polarizing filter on lights AND lens) is very useful for both art and photo copying, but as explained above sometimes you need to dial it back to reveal textures. In the final analysis natural difuse light and a longer focal length lens is pretty hard to beat!