A lot of people go to Cégep in English for this reason too, and it works out pretty well. English is a language you can just catch and learn through immersion, even more in North America where you're surrounded by it. I honestly don't think school is a good place to learn a language. You need to be fully immersed and for it to be a necessity. I learned more spending a weekend in an american household at 8 years old than in a year of English classes in elementary school.
The main difference I see is 2 things, time & immersion. I know less German after 3 years than I did through French Immersion, but I've spent way less time doing it, never had any formal instruction, and haven't spent 7 hours every week day having to talk and listen to German. I know more German than Finnish though, simply because I didn't spend as much effort actually learning Finnish, it all came from immersion.
Also, nowadays, you probably want to speak more than two languages, or at least have some understanding of more than two languages. I'm always amazed by how many people in the US speak either French or Spanish or both (although, sure I have a very biased experience, being in tech circles). Tear down walls, speak multiple languages, it's 2017 and we have a global economy, adapt.
I'm French and I'm not religious about the French language itself. Everything would be so much simpler, including sharing cultural differences if all of humanity just spoke the same language.
English is the interop layer of human communication. It has imperfections but one imperfect standard is better than hundred or thousand of them.
Our common global culture is mostly shared in English. I wish the next generation, or the one after that, all speak English, maybe dialects incorporating local cultural differences. Then we could move forward as a species.
I don't think the friction brought by having so many different languages is worth it.
People are afraid that local identities would be lost. Be the reason people stopped speaking their local language is because most of them don't see a benefit in it. We need to stop the romantic tale and get real.
We still have way too many electrical plugs plus combos for voltage/frequency, also a pain. Just had to buy a new hair clipper this morning because my European one didn't like the US mains.
It seems the stuff that involves direct human interactions is the worst, like having around two hundred different currencies. This one is fairly stupid in hindsight, since there is very little cultural value there. But language, the one thing that we use the most to interact with one another, tops everything with thousands of non-compatible variations… sigh.