I sure wish MLK's dream would come true. I can't wait for the day we are judged by the content of our character, not by the color of our skin.
The problem with this is that it takes a lot of time and energy to know the content of one's character. It literally takes years to really to get to know someone. In this day and age, it's almost a luxury that we cannot afford.
As a species, we have evolved to make snap judgments based on appearance. And without a doubt this favors certain characteristics in our society often associated with success. A crude oversimplification is that professionally, it helps a lot to be tall, good-looking, and white. But whatever. Point is, Malcolm Gladwell write a lot about this type of stuff in pretty understandable terms.
So where does that leave us with regard to race? Not in a very good place, but it's also a place that most other societies find themselves in. Racial bias and racists attitudes exist everywhere, or at least in every country where I have spent any appreciable amount of time, which includes several.
So I am not waiting for the day that MLK spoke of, because I think it never arrives. But that does not mean you should not make an effort to get know somebody before making any real conclusions about them.