Nicely put (and not just cuz your statements mirror my previously posted opinions). I also learned a couple of new things (Cheetah's comic strip appearances and Marston describing her as WWs arch enemy) so thanks.
- Challenge of the Super Friends. It was a major influence on pop culture, and Cheetah being Wonder Woman's archenemy on the show crossed over to the comics decades later.
- Cheetahs are fast. As a character, Cheetah is faster than Diana both physically and mentally. She's almost always one step ahead of her. Are cheetahs (the animal) scary? Not really, they're cute AF. But it fits the theme of Barbara Ann always refusing to be "caught" and redeemed by the superheroine which, for me, is a powerful one.
- Lack of competition. DC Comics loves to team up the various archenemies of the Justice League. Ares wouldn't fit at all, and Circe shouldn't be caught dead with those mortals. There are other villains like Giganta, Dr. Cyber, Silver Swan, etc. that could fit the bill, but haven't been established for the common public who casually watch cartoons or movies. It helps that she's also currently a member of the Legion of Doom which consists of everyone else's archenemies.
- Number of appearances. Cheetah is the only Wonder Woman villain who has appeared pretty much through every writer's run on the comic. As opposed to other villains in her rogues gallery who go decades without appearing. She's consistent, and that helps the image of archenemy-dom.
- She fills a role no other major villain does. Marston created Cheetah to represent female jealousy, and that's explored by later writers in Wonder Woman but never really anywhere else. Female dynamics can't be found in other long-running mainstream superhero comics the way that they are in Wonder Woman and Cheetah's relationship.
She ultimately just needs more appearances akin to The Lies and Godwatch; ones that makes her a fascinating and formidable foe that draws in both new and old readers. After all, clowns aren't really scary but Joker is the most popular supervillain in pop culture history. Powerless men aren't really scary but Lex Luthor is all over the DC Universe. Cheetahs aren't vicious, scary animals but Barbara Ann is ironically the strongest and deadliest of the "Evil Trinity". DC just needs to continue elevating the character instead of, y'know, New 52ing her where she's defeated by Green Arrow and thrown in the Suicide Squad.
In Marston's run, Cheetah was probably the most-used villain outside of Baroness von Gunther (who redeemed pretty early on). She also appeared in the comic strips whereas I don't believe any other villains did. Marston even described her as her archenemy in one of the 40's comics. So that most likely helped her chances.