Once upon a time, people were pressured and obligated to DROP the traditions, dress and habits of their home cultures and adopt ours, because their habits were "unAmerican." If they wanted to BE Americans, they needed to CONDUCT themselves like Americans. The reason that's no longer socially acceptable is because in the 20th century there was a social push to accept the concept of "multiculturalism." In multiculturalism, people become citizens of OUR culture, but still maintain a connection to the culture they came from. Under multiculturalism, you can't say "take that damned turban off, you're American now, act like it!" because America is the great melting pot; so wearing a turban IS American.
What these people refer to as "cultural appropriation" is ESSENTIAL to the concept of multiculturalism. It is the CORNERSTONE of the idea. Embracing, absorbing the cultures of the global community, that is how we as a nation BENEFIT from multiculturalism. The only way that benefits the nation as a *whole,* instead of just dividing us along cultural boundaries, is if we all *share* the myriad of cultures that make up this great landscape. The American ideal of multiculturalism isn’t “you stick to your culture and we’ll stick to ours and don’t you dare cross over.” The ideal is “we’re going to take what we love most about *every* culture, and make it a part of ourselves.”
What's worse is that this ridiculous, backwards ideology is completely COUNTER-productive to promoting racial harmony. You want someone to respect and appreciate people of another race? Immerse them those people's culture. Show them all the great things that COME from that race. This goes doubly for children. Who do you think's more likely to grow up to hate a particular race: a child who grows up participating in and immersing themselves in that race's culture, or a child who is told "no, you can't wear that, you can't cook that, you can't wear your hair that way, you can't celebrate that, you can't do that, because that's THEIR thing. You stick to YOUR race and YOUR culture?" This narrative is PROFOUNDLY damaging to racial harmony, and these stupid SJW's are too clueless to even realize what they're doing.