I think speaking different languages at work can create a us vs them atmosphere that's not good for a healthy work environment.
Also, several states are de facto bilingual.
And then there's South Africa, with 11 official languages.
So I don't think your views are really all that generally applicable.
What you describe is a different scenario. For example, one of my clients was a company in Sweden. Almost no Swedes were in the team. The de facto language for the team was English, even though Sweden's official language is Swedish. The poster's logic would insist that everyone speak Swedish (or one of Sweden's minority languages), even though everyone knew English. While you would say that's fine.
I've also worked for an Austrian company where nearly everyone spoke German most of the time. (Not all of the time; unlike the main thread, I did have chit-chat and work-related conversations. But coffee breaks and lunch were mostly in German.) Okay, I was the outsider. I'm also the outsider when people talk about bands, movies, and sports, since I know so very little about those topics compared to most. That's life?
What about an American company in China? There is a good reason why English is the business language in our office; also, many foreign employees don't speak Chinese but do speak English even though its not their first language. If you want to be international, I think English is pretty mandatory.