The protectionist attitude towards the French language is really hard to comprehend for two reasons. Firstly, all languages are dynamic and are constantly changing. Trying to set strict limits on how language can and can't be used just leads to ossification and is anachronistic. French is not an easy language to learn and get right - I find it inflexible and difficult to learn. Despite my best efforts I know I will never be able to match a mother-tongue speaker. There are so many nuances that I'm just not going to get. It is also depressing to see how pureblood Gauls deride the Belgians, Africans and Quebecois for their use of French.
Secondly, English didn't get to where it is as an international language by the English insisting that we all speak the queen's English. By being flexible and accommodating, English has grown as the world's second language, not solely because of the original Imperial project, but because people find that they can communicate comfortably in the language. To me the issue seems to be that a lot of French people have been taught to fear speaking English and for the most part they are not encouraged to do so. So much so, that a Norwegian once told me "that there is nothing more desperate than a Frenchman trying to speak English".
I beg to differ and when in conversation I always try to speak French. If it does end up that we converse in English, I always try to compliment them on their use of English, because even trying deserves positive reinforcement. I have studied Afrikaans, Modern Greek, Latin, French, Xhosa and Zulu and although I am by no means fluent in any of those, I do feel richer for being able to communicate with a wider range of people.