I agree that we should share and celebrate each other's cultures, and I'm generally opposed to the idea of 'cultural appropriation' being a bad thing. However, in taking aspects of another culture, one must be aware (or at least, one's society must be concerned when spreading the style) of the deeper implications that may come with it.

Wearing the everyday/dress (or traditionally everyday/dress) clothes of another culture in a way that's just meant to be, well, fashion? Fuck anyone who says that's wrong. Wearing the ceremonial articles of another culture in a way that's meant to be fashion? Somewhat dicey, somewhat concerning, though I would argue that it doesn't inherently have to be bad - but one must definitely understand the context of it. Wearing the national dress of a culture in a way that's meant to be amusing or humorous? Eggshells are warranted.

If there is significant inequality, it can very much come across as dismissive or punching down, which is pretty unambiguously bad. Else, it's generally accepted as ribbing without deeper meaning, lacking any deeper context. As an American, I generally don't get upset when someone makes stereotypical American jokes, or putting on a cowboy hat and exaggerated affectation, because I know it's just ribbing. Whereas, as an individual with mental disorders, I can be sensitive about neurotypical folk making mental illness jokes or 'pretending' to be mentally ill as a joke - because I'm not sure that it's not coming from a place of genuine ignorance or malice (or worse - I'm sure that it is), due to the cultural power imbalance between the neurodiverse and the neurotypical being still quite... lopsided.

Were it the other way around - if neurodiverse folk were accepted and Americans were not - I imagine my reactions would likewise be reversed. So too with ethnic groups who are discriminated against by modern society - caution is warranted, and sensitivity to such things is not an incorrect reaction on their part.