Ken Watanabe defended the casting of Memoirs of a Geisha today, likening it to casting non Italians in opera. As I've noted before, I would tend to agree. People have argued that casting other Asians in the roles of Japanese characters stems from the Eurocentric "they all look alike" mentality, but I would argue that ethnic nationalism is in play on both sides. In my humble opinion, anything that blurs the distinction between ethnicity (and ultimately race) is a good thing. One might want to be more concerned with how the West is portraying these characters, and not solely with who they cast.