My family is a "Heinz 57" mix of everything under the sun. There are two native American women that we know among my ancestors, one Blackfoot and one Cherokee. And I have always thought of this as fairly typical of most people in the USA. So the idea that people get all excited about this seems to me a bit...surprising.
It all seems to me like, "Well, yeah, of course. So what?"
I guess it's one more of those cultural differences.