It's intentional. Batman is off-balance and a half beat behind for this whole story arc.
Hitting Joker with his off fist, and revealing his true rage, is evidence that his methodical calculated master strategist is chipping thin, revealing the raw broken child underneath, who is simply desperate to prevent what happened before from happening again, at any cost.
spoiler for Kightfall
It's why Bane is able to casually walk into his home and break him in half in the next (chronological) issue.