First off, I understand that it was used to humanize Superman in the eyes of Batman. It was the first time Bats didn't see him as an alien who could destroy the world, but as someone who is capable of feelings because who doesn't have a mom, or mother figure who made a positive impact in someone's life? So I get why but....

What turned me off is Bruce throughly thought out how to beat Superman and knew it had to be done because of what he saw Superman do with Zod. Bruces feelings immediately changed because their moms share the same name, and Superman just happened to say it. I hated the reaction, maybe it was the over acting by Affleck but imagine if Superman said, "We must stop Luthor" instead of "save Martha". This catches Bats off guard and begins to ease up when Lois Lane comes in and shows her love for Clark, and Superman then brings up the fact that Luthor is hilding his mother hostage and that's what made Bats realize he is a good guy with good intentions in stead of the Martha exchange.