Also, in '79 people were still hyped about Star Wars, a traditional space adventure with rayguns blasting, narrow escapes, amusing robots, weird aliens and cool starships. It was pure pulp sci-fi brought to the big screen. It was flashy and exciting.
Now Star Trek (TOS) had some of those elements, but it was much more distilled. Star Trek had also generally better writing, acting and strong elements of drama (along with doses of humour and even occasional dollops of horror). Star Wars was played on mostly one note while Star Trek ran the gamut of what you could do in sci-fi. Of course there's also the matter of a one shot film (at the time) as opposed as a series.
Suffice to say that Star Wars could well have changed many expectations about what a Star Trek film should have been like. And I'd argue that it has influenced what many people still expect from bi-budget sci-fi on the big screen. Note that the big favourites for Trek in film are: The Wrath Of Khan, The Undiscovered Country, First Contact and ST09. Although not note-for-note they are all flavoured more like Star Wars, most particularly ST09.
Some of TOS' very best moments have nothing to do with starship battles and phaser fights and the like, whether it be TOS or TNG. But for a lot of fans, and in extent TBTB, thats not good enough for the big screen.
Some of the very best films I've seen do drama really well and it's got little to nothing to do with action. It's about effective drama.
Initially Star Trek was about drama dressed as science fiction, and they're certainly not mutually exclusive. But I think a lot of people have the assumption that serious science fiction is more likely dark and dystopic. Star Trek bucks that trend. It can have dark elements, but generally it's meant to be positive: we can have a future and it can be better than what we have.
TOS had its share of straight-up adventure yet it also had its share of thought provoking drama. Seriously TMP and TWOK are two sides of the same coin, but now (and somewhat then as well) it seems like the audience (and TBTB) are satisfied with only one side of the coin. And even that side is being distilled.
For whatever issues I may have with TWOK the fact is it has some good dramatic moments to it as well as some thought provoking ideas, and all that mixed in with dynamic action. Now flash forward three decades and ST09 is all hyper-action without any genuine drama, nuance or ideas worth pondering.
I appreciate a film that can settle down for a few moments to be reflective and expository, but a lot of modern audiences and the people that green-light today's spectacles don't seem to have much patience for that. I recently enjoyed Men In Black 3 and The Avengers, two films with sufficient doses of action and adventure. And yet I've read criticisms where some felt those films were "slow" in some points. Really? So what? I didn't find anything about those films slow. Indeed I found each were rather we'll balanced in their pacing. I appreciated the "quieter" moments as they played well against the more active parts of the films.