More importantly, it dramatically reduces the amount of consumable information available to someone. Instead of being able to learn from tens of millions of books and billions of web documents, now you are able to learn from, if you are lucky, hundreds of books and thousands of web documents.
I am not a native English speaker myself. I am Mexican. Yes, native Spanish speaker which is supposedly one of the top 3 most widely spoken languages on Earth and I must confess that most of the time I don't see the point in reading any content in Spanish anymore (except for some literature - in other words, yes, you probably want to read Shakespeare in English and Cervantes in Spanish, etc)
Foreign news, science, technology in Spanish? all that content is nothing but translations (sometimes bad ones) from the original English source. I see how something could get posted on HN one day and only after many days (usually weeks) it would finally appear in the "Technology News" section of the most "cutting edge" newspapers and media in Latin America or Spain.
I live here in Japan and most scientific papers and research from major universities (like Kyoto or Tokyo University) is also published in English.
I think it's cute to try to keep one's traditions and culture alive but at the end of the day being able to communicate efficiently with each other and do stuff like hacking Android is what keeps the world spinning. Anything else in your way is just extra overhead.
I've never understood the big deal when a language gradually dies out - insisting on keeping it around is insisting on keeping a group of people stuck in an older culture that doesn't work if they want to interact with others in the modern world.
I don't entirely disagree with you either. There is a lot to be said for joining the modern world. But I'd like to see people recording what they can of their traditional culture as they do it.
We'd all like to see a lot of things. It's unfortunate when things are forever lost, but those things are valuable, they will be translated and kept alive. If the people who know them don't consider them valuable enough, or have not been taught/informed by their culture that they're valuable to keep, they won't do it. Keeping a culture using an isolated language doesn't help that either way.
What am I missing? Why teach them skills in a lesser-used language?
(Personal experience from having lived in Guatemala, where there's pressure from outside groups to "keep the culture" and teach kids in their regional languages. As some of the parents of those kids noted, this only sets things against them: Having perfect Spanish offers them much more opportunity.)