Forced? Multiculturalism is forced in the first place. It is a relatively new phenomenon that came with the industrial era. Multiculturalism mainly exists only in the Western world, I don't see big African cities being 30% Chinese and 30% white. If we are the only ones enforcing multiculturalism, the ones who will bring us all the cultural "enrichment" will eventually out breed us in our own homes and the result will either be brown biomass with no identity, history or culture and the disappearance of national borders, or a foreign culture becoming dominant and pushing the Brits, French, Germans, Swedes etc out. It's already slowly happening - the average German family has 1, 2 or no children at all, while the average Turkish family has 6 to 7 children, and the German population is growing old as well while the foreigners from the third world are enriching us by outbreeding us.

Multiculturalism only creates conflict, as seen in Yugoslavia, Africa and the Middle East. It can also be seen in the clashes between Jews, Turks, Kurds, Arabs and Swedes in Sweden. Even in my own country, the Bronze Night happened because the Russians decided to "culturally enrich" us because they refused to integrate. And let's not forget Chechnya.

All of those events could have been avoided if those areas remained homogenous and if the Chechens got their independence.

The reason why nations exist in the first place is because tribes organized into homogenous nations, and bringing in other cultures completely destroys that tribe. Taking part in the destruction of your tribe goes against human instinct.

There is no benefit from multiculturalism besides cuisine. Sure a percentage of an immigrant population is willing to integrate, but a large majority will never, EVER integrate unless force is used - this applies for every ethnicity on earth. For example, in Russia the Udmurts can only host their radio shows in the Udmurt language for 2 hours, the remaining 22 must be Russian, that's forced integration.