If you can't - or don't know how to - treat the cause, treating the symptoms is better than doing nothing. There are plenty of conditions that can't be cured yet, but their symptoms can be alleviated or ameliorated to some degree - Parkinson's, for example.
Bringing it back to the subject of racism, even if you can't force everyone in the country to not be a racist, you can still have laws or policies that try to reduce or eliminate the impact of past, present, and future racism (which is why the voting rights act existed, for instance). I'm not suggesting not trying to eliminate racism, of course. I think part of the point of forced school integration was to try to get kids to grow up together and get used to seeing each other as equals, not seeing all blacks as scary criminals, or all whites as gun-toting racists, or w/e. There are voices in society that are stoking the flames of racism, however, and apparently quite a few people are listening rather than calling bullshit on them. The thing is, it's so easy to convince someone that all X are Y by just giving them examples of Xs being Y and scaring them - the human brain works that way normally, that's how it evolved. It's illogical and unscientific, but it's how you think unless you've learned to think better. (Why is it that way? Well, if you're a primitive human hunter-gatherer and you see a tiger kill one of your clan-mates, which is better for your survival: "That tiger needs to die, but there's no need to jump to conclusions about other tigers on the basis of only one example." or "Shit! We'd better watch out for tigers from now on!")