As far as I can tell it's mostly American culture that considers it to be so taboo.
Remember, all the people that didn't quite fit in in europe jumped ship to america some few hundred years ago to live under their own principles. :D
what I don't understand is, if you don't want your child exposed to things like sexuality, why would you let them play a game that is predominantly played by young adults?
This game is sticking 2000-4000 most likely horny young adults into a single chat room with very (apparently) very anatomically correct and very well made and very beautiful character models.
If you DON'T want your kids exposed to this kind of environment, it's probably not a good game for them to play.
This game will not be made for a 13 year old. None of the final fantasy games have been made for young teens. I would say to truly understand and enjoy the full depth of the games, it would take a mature 15 year old, or your average 17 year old in the US.
That is more the target audience from what I can tell, or the younger part of the target audience. And believe it or not, such details may appeal to that audience.
I've always viewed online games as glorified chat rooms. In other words, you are in the game to socialize in a group of people who like similar things. It's wonderful in the same way that I think church is wonderful. That being said, if you don't want your child talking to a 43 year old man, Don't let them play in online multiplayer games. The focus of most games with a text box is to interact with others. Otherwise you might as well play single player games with increasingly difficult AI.
i'ma cut myself off before I get long winded. This post is already off topic to the OP and really might derail this thread back onto some sanity.