Given that English is already fragmenting (just read a newspaper from Guyana) and with the example of the Arab language (watch an Egyptian try talking with a Moroccan - bring popcorn): I am not sure your advice is a good one. English, like every other language, limits what you can say to what can be expressed in it.

From personal experience, I'd rather recommend to dabble in as many languages as possible: Each new language so far introduced new concepts (of seeing the world, if you will) and forced me to break through the invisible barriers erected by the language I was raised with.

And, finally, if we need a "world language", can we please agree on French? I think it is so much more pleasant to the ear than English... and it saves those who already speak it from having to read "rsvp, please" ever again ;)