When DC picked up the rights to Edgar Rice Burroughs' characters from Gold Key in the 70s, they wasted no time expanding them empire. The At The Earth's Core back-up strip from Korak and the John Carter Of Mars back-up from Tarzan were very quickly spun off into their own title:
Contrast that to Disney's disastrous flop with the John Carter movie:
Nope...hell, eventually they even dropped the "Of Mars" from the title. So if you weren't already familiar with the character, the marketing campaign pretty much gave you nothing (not to mention rendering the "JCM" logo meaningless...).
Hell, why go small at all? Disney should have gone whole hog, pushing an "ERB Cinematic Universe." Carson of Venus movies. Pelluidar movies. Tarzan movies. Korak movies. Crazy-ass crossover movies!!