Why's that a problem? English is the global standard lingua franca. English-speaking people in America only need to learn other languages as a hobby, or if they have a specific interest in a particular country.
BTW, I don't think there's any moral reason why English should be the global language, but it is. I speak French too, and if the global language magically became French tomorrow, I would feel perfectly fine.
There is the hypothesis that because we think in language, the structures of languages limit and shape our thoughts.
Perhaps there are thoughts that are much easier to have in a language other than english, and Americans tend not to have them.
BTW, I don't think there's any moral reason why English should be the global language, but it is. I speak French too, and if the global language magically became French tomorrow, I would feel perfectly fine.