But all Roddenberry did was think it up.
That's kind of a lot, really.
And rewrite most of the scripts in S1, establishing the "lofty" wordsy tone we associate with Star Trek.
And produce/exec. produce the series.
And write/produce the first movie that did well enough to inspire Paramount to make more.
And cocreate the first spinoff series.
That's all.
Being creative, and Roddenberry could be that, is different than being a visionary or promoting some kind of consistent message.
For what it's worth, I see Roddenberry officially credited in some way for five stories in the first year TOS episodes: "Charlie X", "Mudd's Women", parts I and II of "The Menagerie", and "The Return of the Archons". By way of comparison, Gene L. Coon was officially credited in some way in the stories "Arena", "Space Seed", "A Taste of Armageddon", "Devil in the Dark", and "Errand of Mercy" in season one. Five each.
As far as being producer goes, as I said above, Gene L. Coon was probably as responsible for the look and feel of the series as Roddenberry was. The only reason why he doesn't get his due as he should is that he tragically died early (1973). When TOS was nominated for an Emmy for Outstanding Dramatic Series in 1967, he and Roddenberry were each mentioned as the series producers.
Gene Coon's significance should never be forgotten. Even Fred Freiberger is looked at in a more positive light than he's bathed in by some who blame him for any drop in quality in season three. In fact, some even blame Roddenberry for the show's problems in season three, saying he deserted TOS.
At least in the official credits, Roddenberry is not mentioned as a writer in TMP. He may have had a general uncredited influence on the story, but Alan Dean Foster gets sole credit for the story, and Harold Livingston gets sole credit for the screenplay.