I don't understand why many of you feel that the purpose for a television sitcom is to educate. It's not! (my opinion only of course) It is to entertain. When it ceases to be entertaining, it ceases to be.The fact that the Andy Griffith Show had no Black characters is beside the point. It is conceivable that Mayberry had no Black citizens. I never saw a Chinese actor on the show either, or an Afghanstan, or a Japanese. Would it have made the show more entertaining? Maybe. It would depend on the plot of that particular show.
I think actors want to be thought of as actors, not as Blacks, Japanese, Chinese, or anything else. As ridiculous as I thought Halle Berry's "performance" was after she accepted her "Oscar," I think that was the point she was trying to make.
DougR