Let me first of all say, I am someone who is certainly supportive of diversity issues. What I will be talking about here is the GENRE of MULTICULTURAL LITERATURE.
It seems that many people today are missing the point about the definition. It seems that people seem to be thinking that putting ethnic characters into a story makes it multicultural or even racially sensitive. Yes, we all want to see more projects depicting diversity in our literature, and even more voices from authors who live this daily, but again, just putting someone of color, or someone from a particular culture into your story does nothing. Yes, multicultural literature will have characters of different races and ethnicities, but this is not what defines the genre.
I like to think of this genre the same way I think of women's fiction. In the case of women's fiction, it is not about the character, but the perspective and the point of view of the story. The women's fiction genre looks at the world through the female lens. We see how the world is processed through the female psyche. In other words, the "feminine perspective" or "feminine point of view" becomes, at some level, a character in the story.
I want to also bring up the historical aspect of this genre. This is really a tough one. While writing contemporary projects with a multicultural or ethnic feel is easier, finding time periods where bringing this forth is difficult. There will simply be some time periods where that ,multicultural experience will not likely emerge. Regency romance in London will not likely bring forth an African American experience. Yes, you can bring in characters from other countries, but it has to be done carefully so as to not look like it is an intentional move to "insert an ethnic experience" into the story. This is just one example, but I think you can understand what I am talking about.