What would be a problem (and is kind of assumed in what you're saying) is if people stopped learning their native language in favour of English.
Honestly your comment sounds troll like.
Languages bring richness and expression. Im going to guess your from an English speaking country and only have english speaking parents.
The OP originally struck me as a negative comment but reading it again makes me think it was more of just an observation.
I wasn't trying to say having one language is a good/bad thing, but everyone having say, a common language, could benefit all as it opens up more possibilities with people.
I'm not sure I came off right in the second sentence. I meant as if people only chose English and leaving behind their heritage / culture (as amichail suggested below) that would be bad.
Yes, I'm an English only speaker (I believe the majority of the world are bilingual now too), and so are my parents :)
Glad you responded.