The thing is, for the majority of people, English is the automatic choice to learn as a second language as many people from other countries also speak it. For example, when DH had to go on a course in Holland, there were people from spain, Germany and France there, too. What language did they all communicate it? Obviously, English. I can speak German and French, unfortunately not as fluently as I used to be able to.
Also, if you learn English, there are lots of opportunities to hear it - in pop songs, much of the culture is English/American around the world - TV shows, films, etc. When I lived in Germany it was relatively easy to see an English language film in the original. Very difficult over here to see foreign films at all, and also not unless they're dubbed (apart from on BBC4 now, but the sound is usually pretty low).
Another thing is I have found, like many others, even if you do want to practise your language skills, others want to practise their English on you and do that very rude thing of answering you in English, even if you ask in their language (didn't do that when I was much more fluent, though, luckily). I would never dream of answering someone in their own language if they asked me in English.
I would say, however, that learning another language, at whatever age but preferably the younger the better, is very good for the brain and memory. It's very difficult to get good tuition where I live. I tried to learn Spanish a few years ago but the teacher was duff and uninterested.