And lots of those groups were said to not want to assimilate. It's only a few years ago that we were hearing how Latino immigrants didn't want to assimilate because they spoke Spanish at home, etc.

The reality is and I think has always been that older immigrants generally tend not to assimilate very well. Those who immigrate as children and the children and grandchildren of immigrants typically do assimilate, often far more than the older generation wants them to.

I was thinking more of my own personal experience. But even with that you have a point - my father was furious the first time I went on a date with a guy who wasn't Jewish :)