Just offering this in their own words:
Park: [Bringing it to America in 2020,] we were stubborn — we’re not changing the location, we’re not doing stunt casting, the actors should really match the characters. Luckily, the show was already running for multiple years in Korea and Japan and China, and everyone was respectful of what was already done, so we were able to stick to the authenticity of the material.
Aronson: At one point, we had Denée Benton playing Claire, Corey Cott as Oliver and Jon Jon Briones as both [Oliver’s former owner] James and the jazz singer. Then, our thinking was: They’re robots, so they could technically be any background, but if the audience only has a few moments to define the setting, it helps that the protagonists are cast Asian.
Darren Criss (actor, Oliver): Let’s call a spade a spade here — I’m the white-passing Asian of our group, but it is my identity. The AAPI community in the arts is a smaller, if not marginalized, group, so to be up there, I feel that excitement and encouragement from the community at large. It’s important, and I hope this show can continue to have that legacy and be an inspiring call to action in other artistic spheres.
Justin Scribner (production stage manager): I’m excited for Asian artists to see themselves in a piece that’s not about Asian trauma, of which there’s so much in the musical theater canon, like “Miss Saigon” and “The King and I.” That takes its toll. To have roles for Asian artists that just happen to be in Korea, built by Asian creatives in Asia — it all feels like a possible beginning of something.
LA Times
So they changed their tune pretty quickly.