Yeah I saw that, I was like "ugh here we go".
But I think that as a general rule I notice that Samurai are just looked down upon (almost anything asian kind of is) and I noticed that there is clearly not very many asian personas. Just observations.
from the female perspective, i wouldn't be surprised that a lack of female asian characters is due to our culture's perception of their culture. unless you're going to cross dress, the first image of a Japanese woman is that of a geisha. and a lot of people misunderstand geisha to be whores.
even without that misconception, it wouldn't necessarily be fun to play. lots of other cultures repress women, but the women manage to still have a dangerous edge that i feel the run of the mill geisha lacks. even when you think of harem girls you think of women so ridiculously sexy you lose control of yourself. and belly dancers with swords? what a great look-but-don't-touch tension. no one loses control over a geisha, that's the entire point of them, being obedient.
although, someone playing a geisha and joining the Assassins Tourney would be totally badass!