The funny thing is the article says the show sticks to close to the source material, yet what we're seeing is that the creative choices to signaficantly depart from the source material is a huge downfall factor for the show, as it was for Cage.
They always mention the Brubaker/Fraction run as this sort of gold standard, and while it was a really great run, it's not something you can start a series off with.  Danny's return to America, his dynamic with the Meachums, the meshing of mysticism and gritty New York would've adapted easily to a modern era and would've made for good television.
Excuse me if I come off as a 'traditionalist', but there always seems to be a "talking down" of the source material when it comes to articles of both Iron Fist and Luke Cage. It's frustrating because they overexaggerate how outdated the stories were. They were products of their times but they also laid a lot of groundwork that could've been saved for these shows. I get that the Doctor Doom/Luke Cage scene is funny, but it wasn't the end-all be-all for how the series and Cage as a character was written. I mean for god's sake, if Karen Page (who in the 60s Daredevil comics was a stereotypical female love interest) could be written well, it's not hard to do for characters who came a decade later.
That's why I said both Cage and Fist seem to suffer from pressure from a SJW crowd. Both of the characters were born out of 70s era fads that weren't politically correct, and it's sort of what makes the characters great. And rather than completely overhauling them for a PC audience, why not tweak certain elements and then use the nature of their characters for an interesting exploration? The kind of which we might not get from a Daredevil or a Jessica Jones.
I agree with you that certain elements might not want to be kept (doing hero work for money, jive-talking, etc). But completely throwing out the rest does a disservice to what makes the characters great to begin with. What was the point of making Cage from the countryside and a son of a pastor? What was the point of constantly emphasizing throughout the series that he was an ex-cop and ex-military, yet doing absolutely nothing with it? Seems to me they were scared of how the show would be percieved from people all across the political spectrum, causing them to try and be "safe", but causing the end product to suffer. It seems a similar thing happened with Iron Fist with all the talks about him being "problematic".
Cage and Fist can be updated for modern times. The premises they sold us in the trailers and in the promotion were good. Mid 90s hip hop vibe with Cage in Harlem fighting gangsters and drug dealers while being a fugitive and confronting his past? Sounded like a perfect update of the first few issues of Luke's 70s run and would've fit in right with the street-level storylines of the Netflix shows. What did we get instead? A corny, neo-blaxploitation show with muddled fights with a lead actor not wanting to do to much physical scenes despite playing a character known as Power Man. Iron Fist suddenly re-emerging in NYC, causing the Meachums to feel their power threatened and Danny being deemed a crazy person, having to go to therapy, while having to deal with both threats from the Meachums as well as more mystical threats? Sounded like a perfect update of arcs from his original series run. What did we get instead? Corporate meetings, muddled plot, squandered K'un-L'un, no costume, and most importantly, fumbled fight scenes for a character whose MAIN GIMMICK is fighting. What was given to us was proved that not only was the marketing false, but it was a squandering of such great potential to tell really good character stories.
		
		
	 
I don't know, I didn't mind most of those changes you mentioned and I actually think Luke Cage did improve on a few elements from the comics. 
I think Cottonmouth and Mariah are far more interesting in this show then they are in the comics, where they are just generic gangsters with silly gimmicks, here they feel more like human beings.
The preacher thing I thought was a little odd, but it didn't bother me, making Diamondback Luke's brother was a bit cliche though. 
Too me the big flaws of the Luke Cage show was the pacing and Diamondback being a silly cartoon villain.
I don't think lack of adherence to source material was Luke Cage's big problem, I think better pacing, a less disjointed feel and making Diamondback a better villain (or saving him for season 2) would have made the show better, if those problems still existed, adhering to source material wouldn't have gotten rid of them. 
The Guardians of the Galaxy movie is different from the comic, but it still worked. 
Its hard to good fights with Luke Cage, because of how powerful he is, most of his enemies on the show posed no real threat to him, so fights between him and most of the criminals on the show had no tension. Having Luke Cage bust up Cottonmouth's little fort looked kinda cool, but there is no real dramatic tension in that scene, because no one can hurt him. Its easier to do a cool fight scene with DD, where a random punk could get lucky and kill him. 
They tried to do a fight between Luke and Diamondback that was more even but I thought it was silly and didn't really fit the tone of the rest of the show. 
I thought the Luke Cage show was okay, I liked some elements and didn't like others. I did not like it as much as the other two shows though. 
I think some people love the Luke Cage show, some people hate it and some people think its okay, but it does seem like Iron Fist will have fewer defenders. 
But frankly adapting Luke Cage to the Netflix model would always be easier then doing it for Iron Fist.