On the other hand, I don't really think that Star Trek was mean to be plausible (what with the multiple aliens, FTL engines, transporters, time travel stories, etc.). On the scale of sci-fi hardness, it always seemed closer to Doctor Who than something meant to be completely plausible. Does that make any sense?
It absolutely was meant to be plausible. Look at the 1967 draft of the writers' bible -- the first
three pages are a lecture about plausibility and how important it is to write the characters in a way that would be believable in a contemporary show. Character plausibility, emotional plausibility, was paramount to Roddenberry even when he took liberties with the science. His entire goal was to defy the assumption that sci-fi was always fanciful kid stuff and to make an SF show that was as grounded and believable as the best adult Westerns and medical dramas and courtroom dramas of the day. And where the science was concerned, he was one of the first SFTV producers to make any attempt to consult with scientists, engineers, and think tanks in an effort to create a believable view of the future rather than just making up random nonsense. That's why ST has warp drive for FTL travel when most of its contemporary shows and films didn't even acknowledge that the speed of light was a thing that existed, and just assumed you could travel anywhere in the universe using ordinary rockets. (And many of its successors, too. The original
Battlestar Galactica had the fleet travel through multiple galaxies in less than a year even though "lightspeed" was the absolute
maximum that its fastest ships could attain. It also portrayed different "galaxies" as adjacent with no space between them at all.)
Yes, compared to something like Larry Niven's prose SF or Poul Anderson's or mine, Trek is very "soft" SF, but compared to 99% of the fanciful nonsense that passes for SF on film and TV, Trek is actually one of the more scientifically grounded shows, and never more so than when Roddenberry was personally in charge. His aspiration was always to make ST as plausible as he could, even if he often fell short of that goal for reasons of dramatic license or budgetary necessity, and even if his successors have mostly been less concerned with credibility than he was. But it's ST's foundations in plausible worldbuilding and characterization, that original commitment to make something more believable and less stupid than the likes of
Lost in Space, that made
Star Trek so compelling to audiences in the first place. It's sad to me that modern fans have forgotten something so basic and important to the first generation or two of fans, the fact that the ST universe was unique in SFTV for feeling like a future that we could actually believe in and imagine ourselves living in. I guess that's because it's not as unique anymore, that other modern shows have aspired to at least somewhat credible worldbuilding in the Trek vein, e.g.
Babylon 5 or the
Stargate franchise. But the only reason those shows have even as much credibility as they do is because
Star Trek set the precedent -- as it set the precedents for most of the things modern audiences take for granted about SFTV, like intelligence, maturity, conceptual depth, diverse casting, sophisticated visual effects, etc.