Who cares about the culture? The in efficiency due to the lack of a common language is large, standardizing on a language would be an amazing boost to productivity and pushing humanity forward.
Culture is not language, it is the people. Why do people defend language, which can be recorded, yet are silent on the significantly below-replacement fertility rates of some European populations, and the high levels of immigration that will eventually replace the native 'cultures'?
No, culture is not people, it is the shared behaviors and values of the people; use of a particular language is part of that. Immigration may threaten that (since the immigrants do bring their own culture), but immigrants often assimilate into the host culture, or at least adopt large portions of it.
