I have to hand it to Roddenberry, though; even though having no infighting produces a somewhat-unrealistic show, I think there's a solid justification to have the rule anyway. It prevented TOS and TNG scripts from being caught in tension between trying to "say something", vs. entertaining the audience with "low" soap-opera drama (of the kind you see increasingly in the later series.)
I have a feeling this might be no small part in why TOS and TNG are the two ST series that contain 90% of the "only comes up once" sci-fi plots / concepts / worldbuilding that people ever make reference to when talking about "things from Star Trek" rather than when talking about Star Trek. TOS and TNG, while definitely soft sci-fi, were to some degree trying to create 22-minute-long works of literary Speculative Fiction, modelled after the sort of things you'd read in serial SF magazines of the 1950s. Later ST series are emphatically not that, and nor do they try to be.
Some TOS episodes were based on classic scifi stories, like "Voyage of the Space Beagle". Also, Roddenberry employed established scifi authors like David Gerrold to script episodes.
An annoying facet of ST episodes is the morality lessons they push, like on every episode of The Brady Bunch.
I actually found DS9 to be the best of all of them. Aside from the terrible Dr Bashir character, they felt believable, and like any real environment had personality clashes, personal issues, baggage, and of course interpersonal conflicts.
The difference was that rather than turn it into soap opera porn, the characters actually tried to behave professionally (most of the time).
TOS and TNG were sci-fi, even if many scripts varied. Given its time, you could have the classic and interesting tech and society questions there, even if they avoided a lot of the implications. But over time the franchise lost this key part, and so it's much worse for the wear. We could use an actually relevant sci-fi series given current tech.
Unfortunately the 1970s ST animated series gave us the 'trapped in the holodeck' story format. The TNG writers leaned a little too heavily on it.
Yeah. I’ve heard the writers hated it because they had to work so much harder to create drama.
But as you said, I think it ends up with a higher quality show.