UK pushing hard on the multiculturalism agenda yet haven't even managed to unify Scotland, England, Wales and Ireland. More variables - biting off more than they can chew.
Due to once owning an overwhelming empire, I think a lot of people forget "British culture" is inherently "multicultural". A national British dish is chicken tikka masala, a curry, and nobody can tell if it was invented in India or the UK.
This highlights the ambiguity. There is no single multi-culture - it is an adjective that can apply to many distinct mixed cultures.
Some of the pushback is because some multicultures are better than others.