I have no idea why people get so upset about stuff like this. If I wanted to learn how to riverdance I would go take a lesson. The dancers wouldn't be like uhhhh your not allowed cause your not Irish.
Same for clothes.. if I'm a guy and want to wear stilettos I'll go f'in buy a pair and wear them. Might get some odd looks but I sure as hell wouldn't get a message popping up saying "unequipable". Might as well just build walls around each city state and nobody is allowed to ever leave their homeland cause "it's mine!!!!!"