My opinion: if you're making a story and you intentional name drop a race or mention their skin color and complexion, it goes without saying that you should probably stick to that. If you write a script and intentionally market the main character as Chinese, you look for a good Asian Actor to play that role. Look at Daisy Johnson, for example, she's half-Chinese, they say so in the lore. Her mother was Chinese, her father's white. It makes absolutely no sense to cast a blonde haired, white girl for that part, no matter how good she is at acting. Because when you happen to have the episode where she does in fact meet her mother and father and they not only both have brown hair, her mother's visibly full Chinese, and her father's got brown eyes, people are going to question why the fuck this half-Chinese girl has a non-mongoloid facial structure, blonde af hair, and blue eyes.

Regardless, Danny Rand - the Iron Fist - is in fact white. It makes sense to cast a white actor for him. It makes sense to cast whoever acts well for him. I do agree with Knighthawk, though: race, sexuality, gender, they don't matter in the long run. What matters is that the character is good. What I'm looking for, as a gay man, is to be represented by a gay character that isn't defined by his homosexuality. Yet, his homosexuality still matters to me, because I can then point at that particular character and well and truly say that they're a good representation of who I am. That they aren't in a flimsy, nonsense romance that doesn't make sense but to show off that 'oh, this character is gay, so here's a reminder.' I want these things to feel and be organic, not something to tote around like a flag and say, "look at us being so inclusive!" because that is definitely, definitely pandering to a specific audience for views and ratings because if you do wave around the gay flag or the black flag, or any kind of minority flag, you're guaranteed to get views because we people are very much desperate for representation in the media.

That being said, we as a society really need to quash this whole 'Cis-het White Male' default that's plagued the media since white men declared women to be unsuited for the film industry despite building its foundation from the ground up. And as authors. And as pretty much anything. 'Cause if you look back, a lot of shit we have today is because of brilliant female minds. People like Ada Lovelace, Mary Shelley, Marie Curie, etc, built the foundation for a shit ton of things from literature to science to the media itself. We owe them that much.

(Also, it's years after Civil War; there's still a rift between Cap and Tony; Peter's Tony's assistant, so long as Tony keeps his identity a secret. He calls it blackmailing as a joke, but they both know even if Peter refused, Tony wouldn't do shit.)