As a native English speaker who has a Romance language, and two non-germanic and non-romance languages in my studies, I have to say I feel sorry for people who have to learn English as a second language. I would find it VERY difficult to learn as a second language, and particularly so if my first language was a well structured language like the Asian languages I have studied.
I do very well in English (which may sound funny since I am a native speaker. What I mean is that I understand the mechanics of the language well, and can apply them well, and can teach them - not all Native English speakers have those concepts). I find English to be filled with exceptions that do not have satisfactory explanations in virtually every aspect from spelling to pronunciation to grammar rules/exceptions. Some of them come from the fact that English has so many elements of both romance language and germanic language in it, but that is not something someone from an Asian background is going to intuitively know, and I can see that making it extremely difficult to learn. So many things cannot be put together mechanically in English - you just have to know. That is different from other languages I study where I can reconstruct things from rules when I run into something I have not seen before.
Having a common language is a good thing, I think. I just feel sorry for those who do not have a romance or germanic language as their first language who must learn English. :)