Not American but I think I can give some insights.

Take a look at the average white woman in your average american tv show, then take a look at the average japanese or chinese woman in a japanese or chinese tv show or movie. Frankly, even if reality can be different, it's understandable that a man who has seen the awfull side of the white women would see the positive and feminine qualities of the Asian women, at least as depicted in media.

Also anime series often explore themes that aren't recognized in the West and even present reality as it could have been if different values had prevailed. Themes that no western media would dare to present due to political correctness.