Yes, he's such a radically unstable character who tells different stories of his scars for intimidation that he... completely changes his apperance...
Different physical appearance? Oh, big frickin' deal. Maggie Gyllenhal doesn't look like Katie Holmes, but everyone just accepted that they were playing the same character.
And I'm not convinced he was deliberately telling different stories of his scars. I think that his memory honestly changed from scene to scene.
This movie has no further use for the Joker. He's been used. Time to move on to other villains.
Completely disagree. The Joker isn't used at all -- he's completely unresolved.