I remember the heat that Oprah got when she referred to her black female friend as a negress during her show. When people reacted with gasps she went on to explain that negress was a word for a black woman, and that coming from an enlightened black public figure.
Not in support or criticism, I do recognize that his use of language might be a reason for racists and others to celebrate his films. However, he seems to thumb his nose at that notion, or perhaps balance that perception by using imagery of interracial relations, playing himself married to a black nurse, Ving Rhame's character being married to a white lady in Pulp Fiction, Samuel Jackson's character and his "white surfer girl" in Jackie Brown, the sexual tension between Jackie Brown and the white bail bondsman, the relationship between the white lady theater owner and her black employee/lover in Inglourius Bastards. He also revitalized the career of Pam Grier and has provided more exposure for Samuel Jackson, Vivica Fox, and used several other black actors in his movies.
He often pays homage to his love for Black music by using it liberally in his soundtracks and he's spoken often about his enjoyment and fondness of the Black movies of the 70's. I do know that Black films of that era featured uncomfortable sexual images, black women being raped by white men and very liberal use of the n-word. Just saying...maybe that's the connection, I really don't know.