About cyberpunk, it is kind of the opposite of Trek, portraying a world which is shittier than our present not at least to highlight potentially dangerous trends that might lead into this direction.
But nothing in McCoy's comments in the movie has anything to do with that. I mean, if you think that a person losing everything in a messy divorce is something that could only happen in a world worse than our own, then you have an exceedingly rosy perspective on our own world. There is absolutely no connection between messy divorces and cyberpunk. Cyberpunk is about advanced computing technology and corporate dystopias, not unhappy marriages. It's a complete and total non sequitur.
About McCoy, his financial troubles have not been part of the character setup in TOS and if they stood alone I probably wouldn't mind it. But in combination with Kirk's nasty stepfather and Spock's messy childhood it formed a typical coming of age "let's get away from it all" pattern which is fine from a story perspective but dubious from a Trek view as Earth (or Vulcan) shouldn't be a place you wanna get away from.
In combination with Spock's questionable and semi-criminal behaviour and many other little things it created for me an atmosphere that isn't Trekish.
I think people forget that TOS itself didn't depict nearly as idealized a future as TNG did. TOS showed us a future humanity that still had crime and drug abuse ("Mudd's Women"), bigotry ("Balance of Terror"), genocide and murder ("The Conscience of the King"), violent jealousy ("Court-martial"), destructive greed ("The Omega Glory"), homicidal insanity ("Turnabout Intruder"), etc. It was a better world in that humanity had survived its nuclear era, overcome race hatred within the species, and joined together for the benefit and advancement of humanity as a whole, but it was not completely devoid of human folly and venality on an individual level.
And "Spock's messy childhood" in the film was practically a beat-for-beat adaptation of TAS: "Yesteryear," so it's completely consistent with the original portrayal.
STXI on the other hand did not imply that there is anything wrong with dickish people and dubious behaviour but said between the lines that everything is OK the way it is.
I have no idea where the hell you're getting that from. Heck, the whole story is about Kirk and Spock overcoming their respective jerky behavior and becoming better people, transcending the wrongs done to them in their youth. That's anything but endorsing those wrongs.
Same applies for McCoy, he is not forced to go into space but obviously he is economically forced because of bankruptcy to work in an environment which is unbearable for him because of a phobia. This is something I associate with cyberpunk and not with Trek.
"Obviously?" No way is that obvious. All he says is, "Yeah, well, got nowhere else to go. The ex-wife took the whole damn planet in the divorce. All I've got left is my bones." Which is blatant hyperbole and certainly can't be taken literally, so it doesn't really tell us anything definitive about what his actual economic situation is. He could be using those words as a metaphor for his emotional bereftness, his sense that he's lost the life he had and no longer has any personal ties holding him to Earth, and just casting it in more economic terms as protective camouflage. So there's no single "obvious" conclusion to draw from those three sentences.
As I already said, this is just my literal reading of the scene which focuses on the background and a character-focused reading is probably more appropriate.
No, if it were a literal reading, you'd have to conclude that Jocelyn had become empress of Earth and McCoy was an animated skeleton. The whole passage is decidedly non-literal, so whatever you read into it is an interpretation.