When I decided to go to France, lots of my friends asked the same question, "You know French?" or "Isn't language a problem?" Well, in a way, the same also happened when I went to Italy 3 years ago. Having said that, I truly understand where they came from, I mean the questions. I wouldn't say English rules but nowadays mastering English will help you most of the time, of course not ALL of the time.
French people are known to be ultra protective of their own language. It should be known that most French people know English but the general perception is that they refuse to speak the language. But during my last 2-week trip to France, I think the general perception has to be changed to reflect the recent situation.
self explanatory : saw this notice at one of the open restaurant in Montpellier