I just finished watching Kurosawa's RAN.  One of the most striking things about this movie was its use of vivid, beautiful colors.  I feel that it really added a lot to the film, and, for lack of a better word, "illuminated" Kurosawa's visuals.  Actually, illuminate is the perfect word for the purpose color serves.  

This got me thinking about people who prefer black and white visuals to colored.  Jimmy Stewart went to congress to prevent old films from being remade with technicolor.  I can't think of a single advantage of black and white visuals.  Why didn't Kurosawa and other directors use color after it was available?