Netflix's Iron Fist really that bad?

I still think Cottonmouth was the more compelling villain.

But then, I saw him as more of a fallen hero.  Someone who might have been great if he had made different choices in his life, and on some level he knew that.  Diamondback seemed to be just Evil For The Lulz

In this case, Iron Fist doesn't count as whitewashing. At worst, one could argue he's a Mighty Whitey who went to learn Kung Fu from a Asian master and became the undisputed best of it out of all the Asian students. I understand the stereotypical implication of an Asian kung fu fighter, but so is the Mighty Whitey kung fu fighter from the 70s and 80s. 
On the other hand, we still have Shang Chi for an Asian superhero.
However, I take issue with your argument about the Prince of Persia. The Prince IS PERSIAN for all intents and purposes. Voice accent is IRRELEVANT to race. And British is a nationality, not an ethnicity, there is a huge difference between the two. By that logic, Bart Simpson is a woman and Samurai Jack is black.
Now initially I was like "WTF" about the Prince of Persia but over time I forgave it a little, cuz Iranians/Persians being "white" or not was actually more complicated than I thought. Many of them could pass for white, and vice versa Jake Gyllenhal could possibly pass for Persian.

About the whitewashing thing:

No whitewashing here. Iron Fist was always a white dood. I would have preferred for the original character to be asian but he's trope/stereotype either way so whatever.

Actually watching Iron Fist got me upset that Elektra was cast as asian in Daredevil.

I'd rather have asian people doing asian shit but i don't like to see ethnicity changes in characters because I'll be damned if Blade or Storm get changed to anything other than what they are.

Jake Gyllenhaal as The Prince Of Persia was a slap in the face to every north African, middle eastern, and south asian actor out there. Prime example of whitewashing. As was Exodus Gods And Kings. As was Gods Of Egypt. As is Ghost In The Shell. Just my opinion.

Most of those casting decisions I would wager were all about star power. About a century ago, Hollywood realized they could dramatically increase movie attendance by emphasizing the involvement of big name actors, a practice that has continued to this day. So cynical producers out to make a buck always try to go for the big name cast regardless of how they visually fit the role, especially if they aren't confident the film will appeal on its own. And most of the biggest name actors in Hollywood are white (Can you think of a Japanese actress as famous with action film experience as Scarlet Johansson?). Video game movies and anime live action adaptations notoriously bomb, so they are particularly vulnerable to this.

Not saying that these weren't whitewashing necessarily, but I suspect the motivations here were all about money.

Netflix series and such generally don't have the same star power culture, or at least their actors are often not as immediately recognizable do they aren't reliant on star power for profit in the same way. So these might be a better place to put out more non-white heroes.

Relevant:

www.lettersofnote.com/2012/03/i-have-no-ancestors-of-that-gifted.html

Old-school Luke Cage is pretty cringeworthy, both in Luke himself and his villains.  But they managed to update him to get with the times.

Danny's story doesn't seem overly stereotypical.  He just seemed a bit...immature for the mantle of some legendary guardian.

White guy goes to the "mystical orient" and masters new powers/skills is a bit of a trope. Heck, Nolan's Batman fits that trope and so does Dr. Strange.

But to answer raikas' question, they're setting up a "Defenders" series. It's a more street level super hero team in the Marvel comics (The other Netflix series characters being members), Iron Fist is the traditional leader of that group from what I hear.

Except that's not what happens. Danny doesn't just decide to travel to a land of savages to learn their magic, those "mystical Orient" inhabitants rescue him from death and he spends half of his life there, effectively growing up as a native while facing discrimination himself for being an outsider.

And the Defenders show should have just been renamed Heroes for Hire, since the lineup is literally just the Heroes for Hire lineup (Luke, Danny, Jessica, and Misty Knight primarily), but with Daredevil, and also none of the characters present in the show so far were part of the original Defenders team, which since this is supposed to be an introduction to the team a la The Avengers, it seems like it would make more sense to do the OG team composition like the movie (mostly) did. Interestingly, all but 1 of the original Defenders (Doctor Strange, the Hulk, Namor the Sub-Mariner, and the Silver Surfer) have appeared in a movie at least once.

Iron Fist was born from 1970's martial arts cinema, specifically that by Bruce Lee. In that context, I don't really see what's "weird" about it. Bruce Lee himself was known to promote studying martial arts to pretty much everybody, regardless of where they came from, and many of his movies featured non-Asian fighters (Chuck Norris and Kareem Abdul-Jabbar are probably the most famous, who are white and black, respectively). A number of early Iron Fist stories were even all but directly lifted from Lee films, so it's clear hat the character is at least partially a tribute to Bruce Lee, who never wanted martial arts to be seen as a strictly Asian thing.

Even still, Danny doesn't become some kind of super ultra mega master who is better than the Asian people who spent millennia fighting. He's certainly extremely skilled, but he is beaten on a number of occasions by people who are better skilled fighters than he is. I mentioned this before in the thread, the primary reason why Danny is special is because he has the titular Iron Fist, not so much because of his raw fighting skill. Several of his most prominent recurring villains are "Asian" (if the decidedly not-human people from the heavenly cities in the comics can be called Asian), and his arch nemesis, the Steel Serpent Davos, is arguably a better fighter than Danny, being able to match him despite what seems to be an inferior set of mystical abilities. As well, the title of Iron Fist is more of a job than anything, technically anyone can become the Iron Fist if they kill Shou-Lao the Undying, and there have been Iron Fists before Danny, hailing from both the native K'un-L'un and various places of Earth (for example, there was an African Iron Fist at one point in history before Danny.

Incidentally, the character of Shang-Chi, who is de facto the best martial arts fighter in the Marvel continuities, is nowadays practically just Bruce Lee, from his artwork to his mannerisms to his fighting style.

The only people who are concerning themselves with a white character being white are racists. I don't know where you're from, but to use the United States as an example, race isn't even a particularly contested issue outside of university campuses and newsrooms, aka the most likely places to find ideologues and bigots. If you (not referring to you specifically, but to people in general who make things like the race of fictional characters into controversial issues) actually have a problem with someone like Danny being white, and then remaining white in subsequent adaptations and piss your pants in a tantrum because of it, then it just shows that you don't have respect for the material and just want it to pass some kind of ideological purity test and have your insecurities validated.

I know the outrage was inevitable, but the only people getting upset were racist to begin with, so it's not like their opinion on a racial "issue" such as this matters much.