You say it's an issue of demographics and not cultural differences, but I'm don't agree entirely. You even suggest in your own post that "Japanese people" like their men non-threatening. This is a statement about their culture as a whole. You then go on to compare a preference which you assert is definitive of their culture and then compare it to a specific demographic's taste in the United States (in this case, preteen and teenage girls, which doesn't really mesh with the target demographic of a gamer).

Are you suggesting that the vast majority of video games in Japan are aimed at the younger demographic whereas those in the United States have shifted toward an older, more mature demographic? While I'd agree that the average age of gamers is certainly rising in the United States, I wasn't under the impression that Japan's average gamer was getting any younger either. There are plenty of Japanese games (I daresay the majority of them) which are not aimed at younger audiences who still fit into the characterization in discussion. There's definitely a cultural divide here.