The attitude is important, no matter what type of smile he has.
exactly. the origin of his appearance doesn't matter one thing, the trademarks of the character are still there but done differently. it is what the joker is as a character, not what he looks like - on both counts, which he still has.
in my opinion, it is about variety. just like they’ve had him as the red hood, a gangster (and the killer of batman's parents) and failed comedian. here, he comes out of nowhere and we don’t know who he is. his face is smeared with white makeup, hair dyed green, and his smile is cut.
getting the same old thing each time gets boring after a while. sure, it is a winning formula, but still doesn't change the fact that it can get repetitive. this joker is fresh and adds a new spin, while being absolutely faithful to the character.
i find it annoying when people merely look at the origin of ledger's appearance and rule everything associated with the character out.
the dressing is in the performance. as it should be.