I didn't get it but it appeared that the Japanese people were just trying to make fun of themselves (and their dark hair and their flat Japanese noses?)

In that sense, it doesn't seem any more offensive than portraying Californians themselves as air-headed blondes or Bears fans portraying themselves as overweight sausage eaters.

Seems like an inside joke that was meant for a Japanese audience. If they aren't offended, why should we be? (PS, my boss has a nose like that)