Wow! What a rotten experience! I have absolutely no idea why those folks treated you the way they did. All I wished to say is don't lump all Yudansha together as jerks. Maybe it was the mood of a "traditional" Japanese teacher and class? I am only guessing so take it for what its' worth, but from what I understand (and from your post you believe this also), the traditional Japanese are very level conscious. Maybe this caused the practitioners to try to be more "traditional" for better or for worse?
I am curious. Are you male or female? If you are a woman this may have contributed to the disrespect you received. I am not saying it is right, only trying to understand.