What role should diversity play in Oscar nominations?

Stephen King is under fire for saying that “quality” was more important than “diversity” in the Academy’s nominations. So what role should diversity play? Is it possible that the best actors this year just happen to be white? Or does that indicate that there’s racism at play? Are people asking for racial quotas?

In other words: I’m not clear on how the Academy can prove they care about “diversity”. How can they prove it?

Although this question is about the Oscars, the discussion need not be limited to that. This could also apply to college admissions and hiring, etc.