You know, here's a question....
Why was Buck Rogers unsuccessful?
I mean, the Futurama guys proved that the concept would work in satire and even after Trek and Wars, I thought it was a given that Buck (& Flash) were the main influences on the general population with regard to science fiction.
On an academic level, you could say that the Buck Rogers and Flash Gordon stories laid much of the foundation for modern science fiction, building on works of earlier novelists like Jules Verne and Mary Shelley. . .
However, to the general public, Star Trek and Star Wars is Science Fiction.
Other than a pretty die-hard sci-fi geek, who knows anything about Flash Gordon other than what little they remember from that cheesy old 80's movie? Does anybody around remember anything about Buck Rogers other than the 70's TV series and Daffy Duck parodying the older serials (the parody is better remembered to many modern audiences).
The names "Flash Gordon" and "Buck Rogers" are about all that is remembered, and that they were some kind of sci-fi spaceman heroes, but that's about it.
Take Star Trek, Star Wars, Flash Gordon, and Buck Rogers. From a perspective of making a licensed RPG look at the fanbase to draw from:
Star Trek: 40+ years, of which the majority of which has had movies or TV series in production, all in one continuity (more or less), and it still plays on TV nightly in one form or another across the world. Warp drive, transporters, Starfleet, Klingons are all concepts known in fandom and beyond.
Star Wars: 30+ years of being the most famous Space Opera of them all. Six main movies (and several minor movies like Clone Wars and the Ewok movies), TV series (Clone Wars), novels, comic books, action figures, and a billion-dollar merchandising machine. Jedi, Sith, Lightsabers, Star Destroyers, Stormtroopers, Darth Vader, everybody knows who they are.
Flash Gordon: Aside from one movie ~25 years ago it's mostly forgotten serial films from a half century ago or more. Besides the character of Flash Gordon, does the general public know anything about this?
Buck Rogers: The serials of a half-century ago or more are pretty much forgotten, now I'd say the series from the late 70's is remembered more (South Park was able to do a 2-part episode a few years back as a huge parody of it with Cartman frozen for 500 years, right down to the opening theme music and a shot-by-shot redo of the opening). However, unlike Star Trek or Star Wars it doesn't have those memorable images, characters and concepts that have really stuck into the collective consciousness.