Having said that, languages do die naturally for socioeconomic reasons too, and I agree that it's unnecessary, and probably harmful to try to force people to use a language that they have no socioeconomic incentive to use.
Not saving != killing.
Bilingualism has existed in countries for centuries without either language dying out. I'm all for everyone speaking English. I want people to know as many languages as possible. What I don't want is everyone speaking only English.
It's not ok to lose some of our knowledge. Uniformity is bland, dull, uninteresting, and sad. There's a reason why we think knowing a lot of languages is cool. There's beauty to be found in other cultures and their languages. I don't want to force everyone to learn languages, but it'd be tragic if we lost French and with it Hugo, Voltaire, Verne, Baudelaire, Dumas, Asterix and the rest. It just isn't the same in English.
My point is mereley "we got thousand of languages, it's ok to loose some of it, let's spend more energy on making sure we got at least one lingua franca".
- art;
- food;
- social constructs;
- city organisations;
- and slang if you really want your tongue to be part of it.
We don't need to spend time and energy to save old ways of communication. Let's us it to make communication better now.
What's more, anything that live eventually dies, which is something we need to learn to accept. Now we are already spending a lot of energy to save our bodies, and a bit of it to save other living creatures, and I'm on board with that. But saving languages seems a waste to me. Either the system will procude or derive the next linguistic generation, or it will merge the old ones, but all in all, this is something I'd gladly let natural selection kick in.
At the very least, I wish we would all share a minimum of one language. I'm french, I consider my language much more efficient to describe things than english, but I'll be ok to just say "let's make sure everybody at least speak english" and be done with it.
I travel a lot, and the language barrier has never once been a good thing. Best case scenario you have goofy confusion and laughters, worst case scenario you have hate.
Now we don't need to eradicate the language diversity. But it's nor do we need to save it. It's ok to loose some of our knowledge. Yes, even books, stories, ways of thinking. Things die, that's how the system get balanced.
(Plus when we will create galatical aliances with aliens, we will need a earthling language, so let's start now people !)