They copied the novel which featured mainly white characters in line with the very genre it was in many ways critiquing.
The novel did however feature a much larger role for the black psychiatrist, who in many ways represented perhaps the most consistently good person in the whole narrative, who has his very faith if good shaken to the roots by the events that befall him.
I really don't see any issue with the colour of the characters and I'd say that in many ways the preponderance of white characters is itself a critique of the times.
I find it odd you actually thought it was good because it didn't have more coloured characters. It is good the work wasn't PC, but I think you're miss understanding why it didn't have more coloured characters.
Try to be reasonable... its easier than you think...
