Its mostly just a few nutballs who want this.
You answered this question in the previous sentence.
If they want to work at something above picking lettuce or digging ditches then they HAVE to assimilate…and that means learning English. Not just learning to speak it well enough to make themselves understood either…but speaking it fluently, like a native. I’ll give you a point of reference. I don’t know if you are familiar with the Gov. of New Mexico, Richardson, but have you ever heard him speak on TV? If so you will notice something…he doesn’t have a ‘spanish’ accent when he’s speaking. He DOES have a spanish accent when he relaxes…or when he wants too (for effect).
Though born in Mexico, I don’t have a ‘spanish’ accent either…unless I’m back home with my 'mano’s shooting the shit, or with my family for some get together. My kids don’t even speak spanish at all…I never taught them. Oh, they understand some spanish, and speak a little no doubt…they would have too otherwise it would be difficult to understand some of their cousins and my mother (who mostly speaks ‘spanglish’ :)). This was a consious decision starting on my dads part…to ensure that I and my brothers and sisters DID assimilate into US culture and society by making sure that we spoke the language not only fluently but as close to like natives as we possibly could. (WRITING on the other hand is something that has been painful for me to fully get the hang of in English…I get hung up mostly on all the odd spellings).
So, why do they need to assimiliate? Because otherwise you will have a class of people who are isolated with no real chance to improve themselves due to very limited job opportunities. In addition it will cause a greater split between the two groups (i.e. english speaking Americans of all races and those who speak spanish only).
Why do so many immigrants cling to spanish? Here I have to completely speculate, as my own situation was different due to my father. I’d say its because a lot of my bretheren come into the US by less than legal means…and they come in to do very vertically oriented type of work (such as harvest crops). In that kind of situation they don’t HAVE to learn English…spanish is fine and its much easier to just stick with what you know. It becomes a habit to just keep speaking spanish…and of course your kids essentially do what you do, so THEY just keep speaking spanish. It tends to isolate you to the point where you associate with your little groups of fellow spanish speakers without being able to branch out to the wider population. And now a days a lot of schools cater to this…here in New Mexico for instance many of the Charter Schools I do work for have spanish only classes for just such kids…where they are taught in spanish (and so isolated from the rest of the schools population through language).
English is pretty much the defacto international language of science and engineering…and business. Not Spanish. Not only that, it IS the defacto language spoken in the US…if you want to get anywhere or do anything short of heavy manual labor in this country then it is a must to learn it.
-XT