My thoughts are that it's a simple question of need. There is a perceived need in Europe and the wider world to have knowledge of English. It therefore makes it less necessary for people from English-speaking countries to speak other languages. I have been lucky to travel all over the world, learn many languages and meet many people, and I can safely say that - except in some cases where a second language is closely-related to the speaker's mother tongue - linguistic competence is entirely dependent on the individual. The British may have a luke-warm feeling towards learning other languages, but other Europeans are no more adept at learning them than the British are. It's just that other Europeans have a greater (perceived) need and therefore study other languages, and specifically English, many times harder and for many years more.