I can see where you're coming from and agree with the sentiment behind it, but not sure I agree with the conclusion. Personally, I find it really helpful when a certain book or author has a reputation for portraying an certain ethnic character extremely well (or gender, age, orientation, etc.), or even just a diverse ensemble cast that goes deeper than just multicultural names and skin tones.

I'd argue that fiction that does diversity well should be praised, so it can be pointed to by teachers, other writers, etc., as an example of an author/novel that "got it right." Other writers can then read it, analyze it, and learn from it.

Hopefully the day will come when SFF writers who do diversity well are so common that it's no longer noteworthy, but I don't think we're there yet.