why is this even a question.
English should not only be the official language, it should be required.
Scenario time:
<A Firefighter rescues a lady from a burning house.>
Firefighter: You're safe now
Lady: (in Armenian) But my baby's still in there!!!
Firefighter: I don't understand!!
Lady: (in Armenian again) My baby's still in the house!!!
Firefighter: I still don't understand.
<An explosion happens somewhere in the house and baby's arm flies and lands on the ground near them>
Firefighter: Ohh... Shit
Now, you are right this is a melting pot. However, a universal language is needed for communication throughout this country. Since the majority of this country speaks English, since the Constitution and all founding documents are written in English, English should be that universal language.
Now.. no one is saying that people who know other languages shouldn't be allowed to speak them. Diversity is what makes this country so great. But when meeting someone in this country that doesn't speak <insert language here> they should be able to default to English, because most people here already speak it.
Why this is even a question is beyond me. English is supposed to be a requirement for entering this country, and is the standard language taught in most schools. (And should be required in all schools, imo)