Pretty easy to call it an essential skill when English is your first language.
How about you try to pick up some new programming language using only Japanese documentation?
Funny story: Ruby took a while to catch on outside of Japan because its docs were all in 日本語. The Pickaxe was created by basically ignoring all the docs, reading the C, and playing around in the REPL.
Or http://en.wikipedia.org/wiki/Non-English-based_programming_l...
I think it would be really useful for some core information[1] to be made available in best quality form, and in many different languages. This would be things like "How does science work?" and other simple introductory science texts. This would be things like man pages.
This would help people learn the basic concepts while they're also learning other languages. Having short form, excellent quality, science and math educational material available in many languages could do a lot to make the world a better place.
Having read some of your other comments I see that you're aiming the "learn English, it's really useful" to people working at a much higher level than that. I gently agree with most of that - there are many areas where learning English is very useful.
Before ww2 in some technical fields you more or less had to learn German as that where a lot of the research was done - in chemistry it was effectively mandatory.
Before that a natural philosophers had to learn/know Latin.
But it's only true (if it is true, and I haven't seen anything to show that it is) because it's a self-fulfilling prophecy. There's nothing about it that needs it to be true.
"The world needs a common language; you lazy thickos need to speak English (which, coincidentally, is what I speak) otherwise you only have yourselves to blame" is the language of fascists and belongs to the era of Eugenics and other hateful wrong-headed ideologies.
As for anything to show that it is true… have you looked around you? English has very obviously become the lingua franca of commerce, science, and technology. This is not a controversial statement.
Yes it sucks a lot for some people, and no it isn't fair, but that doesn't change it.
What would you have us do?
It is very easy to say that common languages are good when you already speak that common language.
Common languages are great when you've reached the point of doing the job, but they cause extra burden on large parts of the world population and are a barrier to entry for poor people.
One response is to say "Let's teach a simple international English to as many people as possible". Another response is to say "Let's create excellent quality documentation, and then translate this into the majority languages." These need not be exclusive, we can do both.
My misplaced anger you see in this thread comes from my perception of the tone of the 'learn English' side.