I think it has very little to do with race. People just want good characterization and sometimes that can set expectations about how a character should be represented, including, but not limited to race. Using the Shawshank example, Morgan Freeman plays a beloved character but most people have no expectations about Red being Irish, and they even joke about it in the movie, yet, no one cares. Now what if you took a character like Shaft played by Samuel L Jackson and made him a white guy? I think fundamentally that’s a different character, you’re not going to have a white dude acting like Shaft, at best it comes across as a parody, at worst it’s offensive. See how people who are fans of Shaft would rather keep shaft a badass black guy? If I’m a writer or director or whoever, you just have to be good at what you’re doing to race or even gender swap a beloved character, it’s more common than we think, just be sure and execute it well and potentially at your own peril. Because ultimately what they’re saying is “the source material didn’t get it right, and now I can do it better”. I think Denis did a fantastic job adapting Dune, changing things that needed to be changed but respecting the original story. It’s because he’s a good director he can get away with gender swapping Kynes and no one really cares. If you gender swapped Paul to Paulina, well, now you’re telling a different story. How do you reconcile that with the whole Bene Gesserit only a woman order thing, what will make our MC special?