Honestly, when it comes to entertainment, white people are the default, so we ALL relate to them automatically. As a black guy, I can go see a comedy or an action flick with a white lead because, well, it's the norm and that's why I can technically relate to an extent. But vice versa don't always seem to work.
HR,
I agree with what Terry has said. Black people, as a whole, IMO, can identify far more easily with whites than the reverse. This goes back historically. For a long time, and I would argue, even today, whites have been the standard of success, beauty, manhood, feminity, conduct, etc., for many African Americans. So, its not that much of a problem for many blacks to watch movies/TV shows with white leads or that are predominately white.
That doesn't mean that blacks don't want to watch films/shows with black characters as the central character or with black themes. Many do. However, they aren't averse to watching entertainment where they are not the central characters, side characters, token characters, or not even in it because its something we are more used to. On the other hand I don't think that that's something many whites are used to and are reluctant to support entertainment that doesn't put them at the center.
Also, I think because many blacks have also accepted the idea of whites as the default/universal people that its tricky when it comes to 'white' movies or TV shows. On one level blacks realize that Seinfeld for example was a 'white' show that perhaps portrayed a very colorless NYC, but at the same time that didn't stop blacks from watching it. Or for me, I liked the American Pie movies and many 'white' comedies, but I don't see them as 'white' comedies. I see them as comedies with white people in them, but some of the better ones I understand and can relate to even though I am not white.
Spider-Man, Superman, Batman, etc., are white heroes with largely white supporting casts, but their color doesn't bar me from 'getting' what they are all about. I think when a black character is in the mix, the issue is race is largely more apt to come up because, I wonder, if most white writers/creators don't really acknowlege or consider blacks' opinions or perspectives unless there is a racial issue involved, so it ties the black characters more to race/racial controversy and it perhaps makes whites uncomfortable and defensive.
I think the initial wave of black superheroes from the 60s/70s were largely created as a response to the Civil Rights movement and the social changes sweeping the country at that time and their skin color perhaps was the most important character trait. The skin defines the character still. I wonder if this kind of thinking hasn't carried over until today.
In comparison, when you look at contemporary movies with largely black casts or books with black characters, to some extent you get a sense at times of how race can be, but not always, just one part (now it can be a major part) of these persons' makeup.
I would argue that in some black movies and books, you see more well rounded portrayals of blacks than you generally get in white media. Now, racial stereotypes are frequent in both white and black media, but that's another story.