Everyone gets hyped when an American beats a Japanese player. It's a big deal because of the disparity in skill in the communities (not saying there aren't skilled players here but the small size of Japan and arcade scene has developed a good competitive scene, which allows them to get better exponentionally.)
It's the same attitude to when a team beats the American Basketball team (aka Dream Team). China, Russia, Yugaslavia, Puerto Rico, Cuba or whoever beating USA and being hype. It doesn't happen often, so when it does, it's great.
I will say Daigo is pretty professional besides his Diva stuff behind the scenes. He never yells in the persons face, makes comments or whatever. But I think it's a result of his culture.