Gene rewrote many scripts for TOS and no one seems to complain but everyone complains about similar behavior in TNG (over which he was promised complete control). IMO the real question is why promise him complete control and then argue with anything and everything you don't agree with. Why not cancel the show or start your own spin off instead of trying to force Gene to change.
The movies improved without Gene? That's up for debate as most of the movies are bad. Everyone's gold standard is the Wrath of Kahn which IMO isn't bad but also isn't phenomenal either.
Even TNG has only a few really great episodes. TBOBW got everyone hooked but there are a lot of mediocre episodes IMO.
Even now a days the writing of movies and series seems to be "it has be TWOK or it has to be controversial to be star trek
Harlan Ellison complained very loudly about the rewriting process on TOS, so to say that no one complained in the case of TOS is untrue. From
https://memory-alpha.fandom.com/wiki/The_City_on_the_Edge_of_Forever_(episode) (with citations):
Ellison was dismayed with the changes Roddenberry and Fontana made to his story, so much so, that he wished his credit to read "written by Cordwainer Bird", a request Roddenberry denied. Though Ellison had the final right to have his pseudonym attached, he claims that Roddenberry made veiled threats that if he did so he would be "blackballed" in the television and motion picture industry. Despite this feud, Roddenberry listed this as one of his top ten favorite episodes in an issue of TV Guide celebrating the 25th anniversary of Star Trek. In his own defense, Ellison stated he had no real problem with D.C. Fontana rewriting him, but rather with the extent and number of unpaid rewrites the studio and network got out of him, to say nothing of exaggeration-prone Gene Roddenberry telling fans that Ellison's script showed "Scotty selling drugs" (the script did not feature Scott at all). (Star Trek: Four Generations)
Roddenberry apparently denied Ellison's pseudonym request because he knew everyone in the science fiction community was aware that the "Cordwainer Bird" credit was Ellison's way of signaling his dissatisfaction with the way production people treated what he wrote. It would have meant that Star Trek was no different than all the other "science fiction" shows in mistreating quality writers, and could have resulted in prose science fiction writers avoiding contributing to the program. (Inside Star Trek: The Real Story)
Additional recounting from Wikipedia, with citations [
https://en.wikipedia.org/wiki/The_City_on_the_Edge_of_Forever#Development_of_the_teleplay]:
[...]
Dorothy Fontana was hired as a new story editor, replacing Carabatsos. She had previously been Roddenberry's secretary and was well aware of the script's problems from reading the previous versions. When she arrived at work for her first day in her new role, Roddenberry gave her a copy of his revision and told her to try rewriting it. She later referred to that day as "walking into a hornets' nest", and the script itself as a "live grenade". Among the changes in her version was the introduction of the drug cordrazine. Ellison specifically criticized this change, as his most recent version of the script called for an alien creature's venom to cause the symptoms in McCoy. He said that "Gene [Roddenberry] preferred having an accomplished surgeon act in such a boneheaded manner that he injects himself with a deadly drug!"[20]
Justman praised Fontana's version, saying that it was the version that was most likely to be shot. But he suggested that it had now lost the "beauty and mystery inherent in the screenplay as Harlan originally wrote it". He said that he felt bad, because if he had not seen Ellison's earlier versions then he would probably have been "thrilled" with Fontana's version. Still unsatisfied with the script, Roddenberry set about rewriting it once more, entitling the result, dated February 1, the final draft.[20] Ellison later called elements of the dialogue in this version "precisely the kind of dopey Utopian bullshit that Roddenberry loved",[21] and added that Roddenberry had "about as much writing ability as the lowest industry hack".[20] However, Shatner later believed that it was actually re-written by Gene L. Coon and only supervised by Roddenberry.[22] Ellison requested via his agent that he be credited on the script only as Cordwainer Bird. In response, Roddenberry threatened to have Ellison blacklisted by the Writers Guild of America, and the writer was eventually convinced to be credited by name. None of the other writers involved in the work chose to seek credit for the script, since they agreed with Roddenberry that it was important for Star Trek to be associated with writers such as Ellison.[23]
[...]
20. Cushman & Osborn 2013, p. 513.
21. Ellison 1996, p. 8.
22. Shatner & Kreski 1993, p. 221.
23. Cushman & Osborn 2013, p. 514.
From these accounts, it's clear at least that Ellison was unhappy both with the nature of the changes that were made and with the way that Roddenberry mischaracterized the reasons for the changes.
edit - Downthread,
@Maurice points out that of the three sources cited in the Wikipedia snippet, only the source by Ellison himself is to be considered reliable. Hopefully, either
@Maurice can verify that the bottom line can be reliably confirmed, which is that Ellison did complain about the rewriting process, that he was unhappy with at least some of the changes that were made to "City," and that Ellison was unhappy that Roddenberry publicly mischaracterized the reasons why the changes were made, or
@Maurice can clarify otherwise.
