You know that legally you have to be proficient in English to become a naturalized citizen of the United Sates (minus some exceptions for older people)? So the only people who aren't required to learn English who live here are illegal aliens, and older people who naturalized after long stints of living here, and who are older. Everyone else, thru school requirements or naturalization requirements, is required (by law) at one point to learn and be proficient in English. Now, with 11 million illegals, many of whom don't speak English, and their children, who may be legal American citizens by virtue of being born here, also don't learn English until they go to school (and unfortunately some never go to school), this creates a subculture that doesn't learn English. Sure, some fill some important labor roles (many don't, however), but if they didn't have a language barrier then their opportunities would be greater.

I wouldn't move to Mexico, or France, or (enter country here) and expect to be accepted into their country/culture without learning their language and the history of their country.