I realize my name has Yagami in it. But that is because it's from Yagami Iori of the King of Fighters game which I have been a fan of since 1995. Also, I should mention that I enjoy anime (though I don't cosplay myself), that I find the Japanese culture to be fascinating to which I would like to learn more about. I am also an American citizen of the US and that I am proud to be a person who respects others for who they are regardless of their race, religion or gender. I'm not trying boast, nor do I want you to think that I'm trying to be rude to you, but that I am trying to teach you a thing or two.
Anyways, I have a few points to make to you:
1. Not all westerners look the same. Some of them happen to be of Asian (including Japanese) decent.
2. It's ironic that you're complaining on a web site that I'm assuming is American made because of it's title U(nited) S(tates) Message Board when you're, I'm just guessing here, Japanese or at least Asian.
3. Not all cosplayers dress as anime characters. Some cosplay as game, tv, movie and sometimes even real people for example. I once saw a guy cosplaying as Stan Lee
4. "Imitation is the highest form of flattery". People who cosplay as an anime character or one of the things that I mentioned above, is probably a fan of said example. Even if they don't have that great of a costume.
5. "Beauty is in the eye of the beholder". Some Asians, even Japanese, find western people to be attractive or pretty. Some of them are even married to each other. What a shocker, huh?
6. I don't think there's anything wrong with pride, but when you let it blind you to reality and lead down a path of willing ignorance, bigotry, racist views and arrogance, then that's when a line has to be drawn. I also don't think there's anything wrong with not liking some cosplay you have seen and trust me, I've seen some pretty bad cosplayers. Just as long as it doesn't turn you into a jerk.
7. If your goal is to stop all westerners from cosplaying, then I'm afraid it's an impossible task because there are thousands upon thousands of western cosplayers.
8. How about you make a trade with us? Convince your government to give the United States their McDonald's, their Mickey Mouse inspired clothing, their sense of clothing style (Rockabilly, imitation of 1950's "grease monkeys") the national American past time known as baseball, sports jerseys or anything else that is American that has been integrated into the Japanese society. Then, we'll stop cosplaying as your precious fictional, nonexistent, not physically harming anybody by looking like them, anime characters. Until then, we'll continue to cosplay the HELL out of them.
I suggest you think about those points and re-evaluate your view on western cosplayers. Other than that, ja mata ne!