You're misunderstanding my point. I'm not saying we have to fix everything at once. I'm saying that the "one thing that's bad" is not racism; racism is just one particular way the root problem manifests itself. The root of the problem is corruption: people in positions of public trust misusing the power they are granted to indulge their personal prejudices, whatever they are, instead of serving the public. Even if you could wave a magic wand and remove all racism from the world forever, that wouldn't fix the corruption problem; corrupt people in power would just find different excuses for violating people's rights. You have to fix the corruption.
And you won't fix corruption by focusing on one particular prejudice that the corrupt people happen to have, even if historically it has been the most common one (which, btw, I'm not sure is actually true--I think religious prejudice is at least as common historically if not more so--but I'm willing to assume it is for the sake of this discussion). The problem is not the particular prejudice the corrupt people have; the problem is that corrupt people are in power in the first place.