Behind the scenes shit.
Tony Daniels was an up and coming artist DC wanted to lock down to an exclusive contract but he would only do it if he got a Batman book to writer and draw and for him to have major say over the direction of the character. DC agreed but then New 52 happened and Scott Snyder (who wrote Detective Comics while Daniels wrote Batman) didn't want to share Batman with Daniels and bullied editorial to make the two switch books so he got the main Batman and Daniels stuck on the traditionally B-book Detective Comics. And for additional spite, Snyder bullied editorial to force an embargo on nearly the entire Batman Rogue gallery save for Batman #1, where Snyder got to use everyone while everyone else got forced to create lame new villains to use.
This pissed off Daniels, who had gone along with being forced off the A-Book by being told he would get the Morrison treatment and that Detective Comics would be a flashback book with Daniels getting to establish the new canon lore and backstory for Batman and his rogue gallery.... who he now was forbidden from doing because Snyder was a cunt who didn't want to share control over the franchise.
DiDio stepped in to placate Daniels, by telling Snyder that Daniels would be given a single issue to use Joker and write him out of lore along with mandating the use of the "young Commissioner Gordon" design that Daniels made across the board as his new design. Daniels came up with the face removal plotline with the plan promised him, that he would get to write Joker's first major arc in Detective Comics but Snyder backstabbed him with the help of Batman editorial, stealing Joker's first new 52 arc from Daniels and getting him fired from Detective Comics/replaced with the hack John Layman.