Have you considered that when people use the phrase “increase diversity,” they mean across the entire medium? That a movie or book can have, in a vacuum, a fairly limited cast, but if that cast is otherwise unrepresented across film or literature it does increase diversity?

I'd much rather have a diversity of stories with appropriate casting than artificially-induced representation via race-swapping cast members. By all means, use diverse casting for modern and future-facing stories, but give me fewer black elves and asian dwarves in old, exclusively European stories and more stories from Asian, African, South American, etc. cultures.

As a small example: I'd love to see more about Anansi, the African spider trickster god elevated into mainstream media. I can only recall him appearing in American Gods and an episode or two of Gargoyles in the 90s.