It's not about desire, but about practicality. It would take me a 10 hour drive to find somewhere where there is a significant population of "non-native" English speakers. I'm talking about Montreal, and that's the best attempt at comparison that I can make. Hop on a train in London and you're in Paris in 2.5 hours. Rent a car from there, drive 5 hours and you're in Frankfurt. You've hit 2 new languages in less time than it's taken me to find "1".
My mother is from Belgium and can barely speak french now after living here for 40 years. It's simply because the only practice she ever gets is the hour she spends on the phone with her aunt every couple of months. Unless I move, learning a language is just like any other hobby, only more impractical. I'd rather learn a new instrument to play every day than learn a new language to use once every 5 years.
Maybe some precisions are necessary. I am neither French nor American and I can speak French very well. However many of my colleagues did not and since they came to France for short periods of time (1 to 2 years) they did not have much incentive to learn the language.
I think that when you have many non-French speakers in the workforce (this was a research laboratory with a healthy influx of foreign students, postdocs and engineers) then it would be rather nice for the native speakers to speak the 'common' language everybody knows. Otherwise the groups get divided into foreigners and French.
The comments by passersby are quite infuriating as well. When my wife's parents were visiting (not French either) and were talking among themselves we got some angry dude that started ranting (and shouting so that they couldn't even hear each other) about how everybody should speak French. Of course this is an isolated case but still.
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.
