The argument that if you can suspend your disbelief for dragons and magic you can suspect your disbelief for a diverse cast is a dumb argument because you could use it for basically anything.

Most fantasy shows that are in English use British accents. It’s what we expect. But why not use a heavy southern U.S. accent? If you van accept this world with dragons and magic why can’t you accept a southern accent?

If it deviates too far from our expectations then it just seems like a bit.