That's what I don't get. Why were they trying to do an adult show on the Saturday morning block? Did they know that some adults watch cartoons, like the college crowd? Was it an early attempt to capitalize on young adults?
Yes they did do some things that wouldn't have been feasible on live-action, but they also did things like having plant people and cat people. I wish they would have been even more creative with the alien designs than they were.
TOS was marketed in the 60s as being "adult sci-fi", likely in part due to "Lost in Space" being kiddie fare and TOS being comparatively adult (and would have been truly adult, rather than "children of all ages", had "The Cage" been greenlit instead of retooled into WNMHGB. That said, WNMHGB is still above average for the age range and has enough "cerebral" aspects that still made it unique compared to LiS and other fare of the time. Both shows are fun in their own ways, but LiS was definitely aimed at kids, and NBC had spent so much money with the pilots that it was taking a risk in how it promoted the show to bring in viewers. Much to the credit of the genre. Though that said, the premiere episode was comparatively shallow and was hyped up for its monster, rather than the underpinning nature of it being "the last of its kind" and the moral dilemmas that elevate "The Man Trap" above generic monster horror show shlock. It's a tad underrated, IMHO... )
They said the A-word, woohoo!
Between 1969 and 1973, more than two great things happened, but I'll keep the digressions minimal:
1. The game show "Match Game" got a revival with a "modern" format.
2. TAS got made. The pre-teens and teens who grew up with TOS would not be mid-teens or young adults. Of course, how many college-faring young adults were waking up to drink their coffee and snort their powder next to little brother Junior who's antsy for the show airing just afterward where the crazy coyote keeps running off of cliffs.
To cut a long story short*, I'd bet 76 Quatloos (plus 47 Yentoqx) on "Yes, it was an early attempt to capitalize on young adults." Noting the retail album "Inside Star Trek" from 1976 and how Gene says a few things that are definitely aimed at adults of the time as well... they knew a considerable audience did exist, and expanding the franchise into more formats with the actors and makers wasn't going to hurt. It may not have been the biggest audience, but you know they'd be there.
* fantastic song from 1980, BTW