Well, I think a good education all around would be ideal.
However, while I agree with both the for and against arguments, I would have to say my opinion is right up the middle.
I think that countries should learn at least one other language, teach it in schools, etc. Most schools do give students the option to study a second language. However, a lot of the time, these classes are just an extra credit time filler and students don't take them seriously.
So while we may say there needs to be one dominant language, it will only work if people actually learn it.
I'm of the opinion that there should be no world language, but I think the world should know more than one language.
But, that's up to the individual.
The problem when dealing with universial applications of hypothetical situations is they simply never work. The world is still a big place, and there is not a computer, person, or government big enough or fast enough or smart enough to enforce something like a world language.