I'm going to borrow a quote from someone named Kelli on another internet forum:
"The huge difference btw this wave (tsunami) of immigrants is that they come from the same country, culture, what have you. They have such a huge demographic that they no longer have a need to assimilate. It is much different than the immigrants of yesteryear who came from a myriad of places and eventually had to meld into the mainstream culture."
How right she is. (Thanks, Kelli!)
That is a good summary of the problem. We are no longer multicultural, but bicultural.