I've never called my husband "daddy" in front of our daughter. I've referred to him as "your dad," but that's as close as I'll get. I've heard other moms and dads call each other "mommy" and "daddy" in front of their kids, as though those are their only names. Honestly, I find it downright creepy. So here, for your enjoyment, is a list of reasons why I won't ever call my partner "daddy" in front of my kids. It's not exhaustive, but I think it's more than enough to at least help those who are in the "mommy" and "daddy" camp, understand where I'm coming from.
I do remember one instance when my husband was holding my daughter when she was just a few months old. He was sitting on the couch and wanted me to hand him her bottle that was sitting on the counter. "Hey, mom, hand me that bottle, please?" Eh, no. He hadn't even called me "mommy," which would have been much worse, but it was still enough to stop me in my tracks and force us to have a conversation about how we address each other. I am not his "mommy" and he is not my "daddy," so I would much prefer we use proper correct language when we address each other or speak about each other. He laughed, because I'm nothing if not the daughter of two English majors, constantly pointing out proper grammar and spelling, but also because he realized how weird what he had said actually sounded.
Laugh once, husband, but I don't want to hear it again. And I can promise you, all of these reasons are going to keep me from calling you "daddy" at any point, too.