Who is Doctor Obi Nkomo from Harlem Gallery and what is their importance?

Doctor Obi Nkomo is The Curator's good friend. He is also black and likes to philosophize with The Curator. The Doctor's problem is he wants for material things. He cannot stop this want, but also doesn't see anything wrong with it. He's no worse than anyone else. Because of his want, the doctor is not easily impressed, especially by the art in his friend's Gallery.