I don't know about the learning English part ... I'm under the impression that second generation Hispanics do speak English as well as Spanish. But, as far as music goes ... so what? I like their music. It sure beats gangsta' rap. And their native holidays ... once again, so what?
What is different from European (and even many Asian) immigrations is that 2nd generations thought themselves Americans and became wholly integrated. Children of immigrants were usually extremely americanized!
However, that is not what is happening now. 2nd and even 3rd generations out of Mexico still hold their allegiance to Mexico first. the same usually with those from arab countries...
I have to go along with you there. Did you ever notice that Ranchero music is almost indistiguishable from the polka in some cases? I find that really amusing.