Iron Fist always looked lose/lose to me when it came to casting. The character is Danny Rand, a rich kid who ends up learning mystical kung-fu in the fantasy kingdom of K'un Lun and returns to America to fight crime. He's a character who grew out of the explosion of martial arts film in the 70s, and he was usually teamed up with Marvel's blaxploitation character, Power Man. They eventually opened a business together, Heroes For Hire.
The casting was always lose/lose because if Marvel cast a white guy they would be tarred and feathered for not making him Asian - the Marvel Cinematic Universe is low on Asians and has no Asian super-people at all. But if they made Iron Fist Asian they're going to have their first Asian hero be basically a kung fu stereotype... while also riling up the fanboys who react with virulent racism to any change in skin color canon. Me? I would have erred on the side of Asian and make Danny Rand a third-generation Asian-American who has lost all touch with his heritage, which he rediscovers on his quest to become Iron Fist (which is still problematic, since Asian heritage is more than just wuxia).
Marvel erred on the side of whiteness; they've case Game of Thrones' Finn Jones as Danny Rand. It should have been obvious in advance - Marvel has more or less refused to race-swap their major characters, so it's not surprising they kept white Danny Rand very white. And I mean, very white - Finn Jones is like mayonaise on a fresh snow drift covered with Wite-Out. My man is a barrel of crackers.
I only know Jones from Game of Thrones, where he plays the closeted Ser Loras Tyrell, the Knight of Flowers. Which means I thin Finn Jones and I think foppish as fuck; I'll be curious to see what he brings to Danny Rand. He's certainly a real pretty boy. And he seems much younger than the rest of the actors in the Defenders, and much softer. I wonder if the show will play to that - he's a soft rich boy who could butt heads with blue collar Matt Murdock - or if they'll ignore it altogether.
My prediction: the internet will rage and boil for the next few weeks about this casting, people will murmur and complain, Jones will show up in Luke Cage (I'm guessing) and win the audience over, we have Danny/Luke ships on tumblr by year's end, everybody forgets they were enraged in February. Until the next time Marvel hires a white guy.