"he set out to create a character that would endure, with a strong enough origin"

Origin isn't enough. You have to have a *world*. The reason Batman, for one, is so popular is because he has Alfred, Gordon, Dick, Joker, Penguin, Two-Face, Catwoman, Riddler, Poison Ivy, etc etc etc

Making two of three arcs about the same villain isn't, IMO, the right tack to give a character a multifaceted world. It's much more reminiscent of a movie character who only has that one story and maybe some sequels that involve the same villain all over again, but in comic books (successful ones anyway) the enemies vary.