You and salmon30salmon are missing the point. Language is an indicator of 4000+ years of local cultural differentiation. The rest of us europeans are just trying not to say something about 200years worth of adopting cultures. That does indeed create a unique multifaceted community, but surely you realise how much in common you have with most of the rest of the US population?
In Europe these language barriers correspond to sometimes dramatic changes in climate, environment and lifestyle. Finns have very little in common with Italians as far as weltanschauung or culture goes, for instance. I doubt you could find as drastic and systemic difference on your side.
(Just to clarify, I don't mean to imply EU>US, just underlining the difference's depths)
But the point is that the US is 100-200 years of homogenization veneer on cultures ranging from Asian to African to European to indingenous.
In that sense, the US has a broader base of those enclaves within the country and less time to have built a coherent cultural identity between those populations.
Europe, by contrast, hasn't forced the veneer over all of the enclaves (eg, single language), but the enclaves share a more similar historic background.
It's different kinds of diversity, really. Stable multi-components versus broader partial fusion.
(Just to clarify, I don't mean to imply EU>US, just underlining the difference's depths)