You made a very good evaluation lol
It probably has to do with lack of knowledge really. If you study up, like you seem to have done, being European doesn't necessarily make it better. In a way I think a lot of people in North American think anything foreign in genreral is better (not just horses, but anything).
Like you said, we are brainwashed xD Even I tend to think "oh, it's from Europe it must be REALLY nice" Though there are quite a few imported horses I have seen that aren't much, if any, better than the horses bred right here.
Personally, I think the main reason a lot of us think European horses a better is because the "more fortunate" are the people who usually have imported horses (some just buy them to prove they have the money) and we have a tendency to think people who have money buy the best of the best...that's the case sometimes, but a lot of the time it's just a matter of gloating, not because the horse(s) are superior.
I guess that's my view on it, but never really thought on it too much xD