I read somewhere that English the 2nd language of more than twice as many people who speak it as a 1st language. This kind of statistic certainly emphazies the importance of English in the world. Having English as the "common" language of the world has certainly made travel and business ventures easier. I think English is the reason we live such a "global" world these days.
This is awfully broad/vague, but I hope this will be something like what you have in mind:
English has become the international language. This is really quite useful because it allows for much easier communications and interactions between people who need to deal with foreigners. This is especially important, for example, in facilitating international business dealings.
You can argue that this is also something of a negative. You can argue that it diminishes the importance of local languages and robs the world of cultural diversity.
The English language has become the international language and is very helpful for whatever pleasure or business we have to conduct in other countries.
The negative part, and this is a very perssonal opinion of mine, is for instance when we are in a third world country as I was in Iraq last year, you have no privacy of conversations when standing amongst them. We had interpreters that of course could understand everything you said. When we would go to meetings in Bagdad, you couldnt really say anything personal in the English language about them (lol) without them knowing what you were saying.
Anyway this is just a thought. Dont know if it will help you or not.