This is interesting discussion. I think the writer should make his or her decision about how to use his/her voice. Some writers just like to tell an exciting story. And I think sometimes we get sick of the struggle and just want to be entertained. And that's okay, For me, personally, I try to make a statement and entertain folks. But, in a lot of my writing I focus on global struggles that affect everybody (my Immortal series). Pollution, for example, wouldn't be labeled a "black struggle," but it affects black folks just the same -- and sometimes worse if it's in a poor neighborhood.
In my Mona Livelong series, I have touched on racism, but it's an alternate world which I for me makes it easier to write about. And I explore it with my characters ... there's always a reason why a villain is a villain.
Funny thing, I never make these decisions before I start writing-- they just jump into my head.