There's extreme wealth inequalities between EU countries (we're talking about one order of magnitude in the extreme cases), language barriers are the main things holding back the demographic crisis that would come from mass economic immigration within the EU.
> Let's face it: our culture (all across the EU), is American, anyway. It's stupid to pretend otherwise.
EU is a big place (and so is the US). Perhaps you've mainly visited major urban centers of both and so don't see the rather unique cultures both hold.