I think there's some dissonance going on in this thread regarding what the reaction was to Ledger's casting versus the reaction to this first image of Leto as Joker.
When people were crying fowl about Ledger, it was not about the look, it was about the news he was cast. Much like Michael Keaton's casting as Batman, most people just knew Ledger as the pretty boy from movies like A Knight's Tale and 10 Things I Hate About You. It was when the first images of him leaked and the first teaser with him specifically that people got excited about him based on his look.
With Leto, people were fine with the casting. He's proven to be a versatile actor, capable of working in much darker material like The Thin Red Line, Fight Club and Requiem for a Dream, and even is something of a method actor like gaining extra weight to play Mark David Chapman in Chapter 27, so his acting ability was never in question, most assumed The Joker would be in good hands. This negative reaction so far is only based around this official photo being released.
This is essentially the complete opposite of the Heath Ledger casting / reveal. Jared Leto's casting was a positive, the release of this photo is seen as a negative.