Yes, previous groups of immigrants assimilated. The major Catholic immigrant group, of course, spoke English already - the Irish - but there were others, most notable the Germans. Which, incidentally, was a major source of contention several times during the 19th and 20th centuries, mostly because German Catholic felt short-changed by what was becoming an overwhelmingly Irish episcopacy. There was even a request sent to Rome for a separate German diocese. So obviously, despite the fact that this generation of immigrants felt strongly about learning the language, their nation-of-origin identity was still very important to them. This is nothing new, nor is it a by-product of these bilingual times.
Secondly, regarding the flip order for these poor immigrants from Latin America and Mexico to just learn English and get over it: Maybe these folks are too busy working a couple of jobs - probably supporting your business or leisure activities in some way - to make time for class right this minute. They probably want it more than you think, but surviving and making a little extra to send back home is probably eating up a good 16 hours of their day right now.