If I want to see a whole movie dedicated to Dent’s good intentions and tragic downfall, I’ll watch The Dark Knight. Just because Batman shows up in the opening scene fully formed in The Batman, doesn’t mean there won’t be effective storytelling and character development. I don’t want to see another origin story for Bruce, and I feel the same about Harvey. Through dialogue and a flashback sequence, you can paint a pretty damn good picture of who Harvey Dent used to be & what he’s become. Less is more for the antagonists.
It seems like this series is not about the villains. It’s following Batman. Through his eyes we see Penguin, Riddler and Catwoman. I’m sure that’s also the case for Joker, Two-Face and whoever else comes on board. Good. I’m tired of villain origin stories inside the hero’s movie.
Also, the whole point of Two Face is to see both sides of the coin at once. We get Dent and Two-Face sometimes in the same scene. That’s what Nolan never tackled. So that’s why another full blown Harvey Dent movie is unnecessary.