If you could choose one other 70's tabletop game to replace D&D's place in the world, cartoon and all, what would it be?
The smartass in me wants to say Bunnies & Burrows, but my real answer would probably be Ken St. Andre's Starfaring (1976). Even just about half a century later, the set of literary inspirations it draws on is – as far as I'm aware – unique among published science fiction RPGs, and many elements of its setting anticipate the development of transhuman sci-fi as a distinct genre by nearly twenty years.
I'll freely grant that a lot of its material isn't a great look by 2021 standards, but then, the the same could be said of just about any 1970s tabletop RPG, including early Dungeons & Dragons. (Anyone else remember the Random Harlot Table?) On the plus side, you get illustrations like this:
