Jor-El's story could be epic, sure. But a Superman movie should be about Superman, and Jor-El's role in his mythology. Not about just Jor-El and his personal struggles. In Superman mythology, Jor-El is essentially responsible for saving Kal-El's life, and indirectly, for his Kryptonian heritage, and that's about it in terms of the big picture. Could you make him more relevant? Sure, and maybe you should, but you don't have to. Richard Donner actually tried to make Jor-El more relevant than he'd ever been to Superman's overall story by having Jor-El "train him" and provide him with his mission on Earth.
See, I don't neccessarily have to see Krypton explode, or Jor-El send Kal-El away, or Jor-El's struggles with the council in the first movie. I don't even neccessarily want to see Ma and Pa Kent finding him. I want to see the thematic relevance of all that. I want to see an element Superman movie, not one that merely ticks off the basics of the origin story.
STAS was fun, but I don't know that it's first few episodes should be used as the blueprint for the next Superman movie. Braniac being tied to Superman's origin could work, and is all well and good. But I say you make a movie that deals with the origin of Superman in the public eye, a movie that hints about where he came from, not a movie that is directly about where he came from. He need not even know he's FROM Krypton to start with. That creates conflict, drama, etc, and it gives you somewhere to go in a sequel that is dramatically satisfying. You start with Braniac, and his ties to Krypton right off the bat, and where do you go? Right to another alien threat? Zod? Darkseid? The Death of Superman?