The idea of being able to essentially species change a Klingon into a Human with TOS-era Klingon medical tech sounds impossibly advanced for what the Klingons are known for.
It's also something that literally happened in a TOS episode that almost everyone saw and liked.
Personally I'm glad those transphobic fucks aren't allowed anywhere near Star Trek.
Then as someone who does know a lot about this stuff I can tell you that you are making a lot of assumptions that are not the case.
It's one thing to do as a one-off gag or a nostalgia bit. It would not have been possible to take seriously for an ongoing series in 2017, except for hardcore fans that don't need to be sold on it.
So why can't you do that here?
It’s 100 years later.
TMP isn't.
“so what about Kang, Kor, or Koloth? How do they look right now?”
Like Klingons.
...That's literally what happens in the Dune books.
How many more years before the crude, gritty aesthetic of Star Wars suffers the same fate as the crude and campy aesthetic of Star Trek?
People complained about exactly that during the Prequel Trilogy.
I mean... not that much. Daleks have gone through three redesigns just since the show went back. Sontarans went from the world's most unconvincing rubber masks to makeup. And how many eyes do Silurians have-- two, or three?
because apparently Star Trek, unlike every other fantasy and science fiction thing I like, is Forbidden from being treated like a secondary world that should have its own internal consistency.
Nonsense-- other long-running universes encounter retcons and visual redesigns all the time. Quick, how old was Dick Grayson when he first became Robin? What color is Superman's S? How old was Magneto during the Holocaust? What happened to Luke's father? Did James Bond fight in World War 2, or participate the Cold War?
That's not canonical, merely a popular theory.