Firstly I like that there are so many different languages in Europe. It makes travel more interesting and we have a wider variety of culture (e.g. music in one language doesn't always work in another). However if the problem is that ideas don't get spread around I don't think that's true. Travel to any country in Europe and you won't have much difficulty finding people who speak English very well. They prefer to speak their own language but communication with non-speakers isn't an issue. When you throw in the fact that most Europeans are also quite well versed in another European language other than English (French, German, Spanish being the main ones) finding a common language to communicate in is really not a big deal. Of course it depends on the age of the person you are speaking to. I find that older people (above 40/50) aren't as muti-lingual but younger people due to travelling more and learning multiple languages in school don't have a problem.
Greece's island fragmentation gave them the greatest fleet of their time. Europe's languages might actually be it's strength.