I'll take a stab: the world is fundamentally unfair to a certain extent...but we want to reduce that. In a perfect world, there should be no restrictions on immigration. However, we live in a world with vast inequalities and differences in culture, wealth etc. So while nationalism is unfair we live with it for now. Racism is analogous, but it concerned people within the US border, governed by US law, already part of US society, and its important for the fairness within the country and society that it be eliminated (not to mention that minorities did protest against institutional racism....and they could not be deported as they are US citizens).