... when does the actor's race matter? It would when the story is about racial tension, I suppose: it'll be a century or more before you could have a white actor play Malcolm X. But most of the time, it doesn't matter that you've recast, say, Johnny Rico from Starship Troopers as a white character.

Regardless, the criteria above about actors needing to match their characters in every detail is risibly ahistorical and unmoored from any principle of film or theater; it's pure applesauce, rationalization pretending at erudition.