Coming from a Game Informer interview with Rocksteady's Sefton Hill...

"We said, 'Make the game you want to make.' We didn't want to try and influence them from afar. We wanted them to be really passionate about the game they wanted to make... We didn't want to try and be directing from across the Atlantic. We were quite busy."

Both Warner Bros. and Rocksteady agreed that a 3-year wait for the next Batman game would be too long, which is why they called in WB Montreal to create Origins.