If you read my other point it's not even about how close to classic Joker his character will look but how they presented him with this "edgy", "hip", "modern" look, which regardless of what the Joker is wearing is not how you'd describe that character.
Either way the performance will count the most but the image is still silly.
I don't know how this forum feels about reposts, but what I said before on this is particularly relevant here:
Can we not at least agree that there are far fewer and far less significant changes from source in Leto than Ledger?
A VAST amount of Ledger's Joker was either greatly separated from source or made up completely. And most of us forgave it, because we could see Nolan understood the mythos and liked the character and thus the Joker we know was still in there.
I think people are having a fearful reaction (And fear leads to anger, anger leads to hate...) based on assumptions about the thinking behind this image. The tats, the rings, the "grill" seem to suggest some guys with sketch books trying to turn the Joker into a New Jersey goth or something.
Here's the thing, though: Whether you liked them or not, the costumes in MoS were EXTREMELY well thought out. If you watch the behind the scenes stuff you'll see how much back story went into every minor decision. Snyder has made a point to say that he really really tried to include the briefs but it just didn't work with any of the concept designs that included them.
Snyder might not be directing, but he is supervising the DCCU, and they're going to be at least seeking his input. That means Snyder is going to be asking for reasons behind everything, whether or not those reasons are revealed in the movie (Most of Krypton's engineering and fashion isn't revealed in the movie, but there were volumes of thought and design behind it).
In other words, nothing was just thrown into this Joker because it kinda looked cool or because it made him grittier. There's a purpose, and that purpose is likely rooted in the Joker's story. You may ultimately disagree with how that purpose translates into the movie, but you shouldn't fear that there is no purpose at all.