It's difficult for me to take this stuff seriously, but to add to Niara, there also had decisions to be made for what dialogs and situation such a "physical attraction" could be an option. Not only in China it most often would be seen more as a problem of mental sanity if a woman or man would show deliberately intimate parts of her/his body for example to get better information about the way to the next train station (or the place of an explosion) or to get her/his buns (or potions) for less money. In more intimate and complicated situations sexual attraction might be used, but surely not by simply showing "the boobs", that's ridiculous. Maybe in front of the toilet in a bar when all participants are very drunk it could be valid, but should that be simulated?
If sexual attraction can be used (and it for sure plays a role in interactions sometimes), than not only the sexual orientation has to be modeled but also sexual visual preferences. There are a lot of men and women in exist who would receive nothing if they "flashed their boobs" in front of me. That cannot be simulated by the roll of a dice because it's an all or nothing thing.
So the effort would be high to implement such a system and the gain would be quite small in my opinion, if you wanted to avoid extreme stereotypes.
