I honestly don't know how they haven't yet, I'm not sure about the other sims games since I've only ever played 4 and medieval.. have they ever done that sort of theme before?
Right now about all they have are basically Chinese food signs and a couple of rather unrelated statues, and the ninja costume i already mentioned.. and that's it, I'm hoping that them adding the question to their survey asking about people's interest in eastern/Chinese themed stuff is a good sign.. and goes over well.
It would add a lot of options to the game to add some far eastern stuff to the game, we've got tons of western/gothic/medieval/modern and American stuff already..
So some traditional Chinese or just generally far eastern stuff would be a nice change of pace