Americans generally have a fetish with French, as do most (but not all) well-educated English Canadians. Just look at the "Education" section of iTunes podcasts: Five of the top 15 are French classes. French has a romantic place in the international Anglo's imagination that other languages spoken by as many people (say, German or Russian) simply do not.
The problem for the unilingual native Anglo Montrealer (and apparently some other Anglo Canadians) is that French has been a source of frustration for their whole lives. They couldn't make friends with someone, couldn't tell what meat was on sale, couldn't get a certain job or promotion or certification, couldn't understand what the Hydro guy was saying. They've gotten dirty looks from police officers, civil servants, waitresses, and merchants when their unilingualism manifested itself. Additionally, they don't get the free pass that tourists get. These people will never see French as a cool Romantic language. It is the language of the oppressor, just as English is the language of the oppressor for some unilingual French Montrealers.
So, you may ask, why wouldn't they just learn French, given all this adversity? I tend to blame the parents. No native Montrealer should grow up unable to carry a basic conversation in French; to be honest I don't know how they do. But if they don't speak French by 13, it's going to be tough. For people without an affinity for languages it can be extremely difficult. Some people respond well to such adversity, others don't.
People who don't speak French, have difficulty learning languages, and are uncomfortable out of their comfort zone find it easy to stay mostly in their neighborhood. They know they should get out more and learn French, but they don't. For better or worse, you can still live very comfortably in certain areas of Montreal without speaking French (why Ocoq chose the Plateau is beyond me), even if you can't really begin to appreciate all the city has to offer.
So they stay in the neighborhood they grew up in, be it Westmount or Hampstead or the West Island. They may occasionally go party on Crescent street, but it's more likely to be a bar on Sources. Every so often, they'll take a French class, because they know they should, but it will end in frustration, because it's hard to do 5 hours of practice every week when you live in the West Island and your kids or your neighbors or your neighbor's kids think your accent is just too funny.
To be fair, I could be talking out of my ass. I actually don't think I currently know any native Anglo Montrealers who can't carry a basic conversation in French. I think they're a dying breed, particularly among the educated. But I do know Anglos who have moved to Montreal from elsewhere in Canada and the U.S. Sometimes they manage to learn French, sometimes they don't. But when they don't, they tend to see it as a personal failing, and the resulting frustration is not felt to be a violation of their rights.
I've gone on too long...