In this way, you also learn more about your OWN language. You discover what makes your language unique and what it lacks that other languages have. English speakers learn where a lot of words they use are derived from, so they are able to more fully appreciate a word when they decide to use it. When you study another language, you learn what the formations are called and you find them in your own language. Technically, your skills in English would improve profoundly through learning another language.
Language IS, after all, human communication.
The more effectively we communicate, the more we benefit from it, and the closer we feel to other humans. In a time when cultures are being forced together and are mixing daily, it is important that we understand where each other comes from. I'm not here to preach the whole outreach shit to you, I'm just saying that trying to talk to someone who doesn't speak your language very well is like trying to talk to a deaf man. The bottom line is that I think America is doing its future generations a huge disservice by phasing languages out of schools. I just wanted to drop some thoughts on languages, and not dissect and compare the various arguments and come to a formal conclusion.