It depends what context the show is in. I mean, as sad as I think it is, a significant portion of the population exclusively associate themselves with people of their own color. So a main cast that is predominantly white in New York is still believable. Especially depending on the socioeconomic situations of the characters. The problem arises when that main cast goes outside of their inner circle within the television show, and magically everyone in the city is somehow White. Alright, the main character, the main character's girlfriend, the main character's family and the main character's friends are all white, I can dig it. But when that main character goes out into a New York neighborhood, goes to a restaurant, goes to a movie theater, etc and everyone is White... then yeah, that's pretty damned annoying.