I don't want to turn this into a discussion of what does and does not constitute racism to the world at large.
That having been said:
It was published in 1974. That was a long time ago and a lot of attitudes have changed since then and many more are changing now. Consider it for the time it was. Do you have a problem with Mark Twain too?
Further, people with a reasonable view of the world don't consider black people pointing out that they are, in fact, black people, out of the norm. I've heard black people tell me they do things a certain way "because they are black". They say they drive like black people, walk like black people, laugh like black people and live on "black time". Because they are black. My black friends (yes, I do in fact have black friends) call me the honorary brotha because I eat chicken (specifically wings) like a black man (I put the entire wingette in my mouth and manipulate all the meat off the bone and what is left wouldn't satisfy an anthill. It's a talent). Also I eat collards, pig feet, short ribs, and many other foods that are stereotypically eaten by black people. Sadly it's more a result of growing up dirt poor in the South (you know, just like black people did 100 years ago). My black friends and I occasionally swap the latest joke at each others' expense. Does that make me a racist? No it means my friends and I are comfortable with each other and the disparities in our pigments. Perhaps African-Canadians do things differently. I don't know, I don't live there and I don't know any. But we let our black people call each other the N-word and if they aren't tolerant of the use of that particular word, we let them follow their own moral compass and police themselves. I don't use it out of respect. I call my black friends "My Ninjas". They're cool like that. Am I a racist? They don't think so.
I mean shit, I'm white (actually I'm Irish, Dutch and Ashkenazi so I'm practically transparent) and I don't care if people call me Whitey. Call me Whitey Ford, I sing the blues. Ask anyone.
Also consider the fact that black people (like Asians and Aboriginal peoples and Indians and Arabs and every other demographic) WANT to be recognized in the arts, in the media, and yes, in literature. How do we do this if we don't identify them as black (etc etc et al)?
Or we could just call each other Ninjas.