My take is:

A person who has legally come to the country, values the laws and history of the country and wishes to be English should be given the oppourtunity to do so. The liklihood is that first generation immigrants will not integrate fully, but the second can.

No country is set in stone. All cultures drift over time. Coming here and adding something to the mix is fine - indeed a good thing. Coming over here and speaking a different language, trying to follow different laws, a different religion, different schools isn't.