No one would argue that learning about other cultures is worthwhile. BUT they aren't just interested in teaching students about other cultures, they want to build these cultures up by tearing our culture down. In some instances they rewrite history to such an extent that students have no idea what actually happened or why it happened.
Elan Journo has this to say in Multiculturalism's War on Education
What these textbooks reveal is a concerted effort to portray the most backward, impoverished and murderous cultures as advanced, prosperous and life-enhancing. Multiculturalism's goal is not to teach about other cultures, but to promote--by means of distortions and half-truths--the notion that non-Western cultures are as good as, if not better than, Western culture. Far from "broadening" the curriculum, what multiculturalism seeks is to diminish the value of Western culture in the minds of students. But, given all the facts, the objective superiority of Western culture is apparent, so multiculturalists artificially elevate other cultures and depreciate the West.
Multiculturalism has lead to politically correct policies in today's public schools and universities that is stifling new ideas. Students are taught to conform to the "policy" without question, without thought. Students who don't conform are labeled intolerant.
Multiculturalism:The New Racism
Racism, not any meaningful sense of diversity, guides today's intellectuals. The educationally significant diversity that exists in "the real world" is intellectual diversity, i.e., the diversity of ideas. But such diversity--far from being sought after--is virtually forbidden on campus. The existence of "political correctness" blasts the academics' pretense at valuing real diversity. What they want is abject conformity.
Multiculturalism does a disservice to all. Thankfully homeschoolers are free to buy textbooks that tell the truth and nothing but the truth, they are free to have a multicultural free zone, and to forget the political correct agendas being promoted in public schools.