If you are referring to the idea that children need to spend their precious school hours only on "useful subjects", then you ought to consider that many young people these days mainly learn English through osmosis while watching television programs etc. at home. So, whether time during their school day is spent focusing on aspects of their native language or not doesn’t make a difference for their ability to communicate internationally.

As for "Efficient communication is probably the most important factor in peace", that kind of idealism doesn't hold in practice. The peoples of Yugoslavia could efficiently communicate with each other because they shared essentially the same language, but it still didn't stop them from descending into brutal warfare. Even today, peoples of two antagonistic countries can often communicate with one another in English, but they go on despising each other nevertheless.

Interesting! Would you like to expand on that argument?