I think the notion of language, culture and borders is natural for the human species - as it is for a lot of the higher animal orders.
The main problem with 'multiculturalism' is that it is an abject failure. The notion that we all embrace everyone else's culturual identities is farcical in the extreme.
Tolerate - yes, no problem, Accept - of course, that is the way civilisation works. Assimilate - no, that is simply not practical. It leads to the farce of a London Council trying to enforce 'fasting' on its Council members who have happily met alongside Muslim colleagues observing Ramadan for years. What next? Making Muslim Council members take ashes on Ash Wednesday, give something up for Lent, attend Midnight Mass?
Cultural diversity should be celebrated and enjoyed, not blurred and neutored. Society is a diverse place becuase humans are a diverse species.
In response to your question - obviously America is the model of choice - they seem to think it's Ok rto force their ideas of freedom on the rest of the world, so why not takew the pressure off them and just accept that they are the best?