[...] I see little evidence outside fandom of Trek spawning some great pan-national awakening resulting in some social transformation. Trek was and is a "pop culture" phenomenon with a high degree of public awareness to be sure, but to ascribe it the status of a larger cultural movement is more than a bit of a stretch.
I would say that, if anything, it's Trek
fandom that is the larger cultural phenomenon.
For whatever reason, the show has touched each of us in different ways. We gathered together as a community to express our appreciation, and in response to that, Paramount has made five more series (I'm including TAS here) and 11 movies, and hundreds of novels have been published.
That's the phenomenon. The fact that this thread has gone on as long as it has, with no consensus being reached as to why the show is so popular, is evidence that there
is no one reason. It just is. We all have our own reasons for enjoying the various series, and there's nothing that says that we all have to have the same reason for being fans. Hell, we're not all fans of the
same series, necessarily. Some only like TOS. Some only like the shows that came after TOS. Some only like one or two of the shows. But we all like something from the 46 years that the Star Trek franchise has existed.
Other shows and films may have done the same things as Trek. Some have done things better, others worse. But for many decades, Trek was the main reason for the existence of media science fiction fandom. We may remember other series fondly, but you didn't see
Twilight Zone,
Lost In Space, or
Tom Corbett, Space Cadet conventions everywhere in the 1970s and 80s. (Okay, Frankie Thomas was to be a special guest at the 2006 Worldcon, but he died about three months before the convention.)