Our kids call us by our names. They just picked it up from other people calling us by our names. They use mommy and daddy as nicknames. We never encouraged it or discouraged it but I do like it. It shows that we're equals as human beings, all inherently worthy of respect. Also, if our kids were to get lost they'd know what our names are instead of just mommy/daddy (they're 4 and 2).
Even as an adult I'm not comfortable using my parents' names and that kinda bugs me. When I was growing up I had a couple friends who used their parents' names and it seemed so weird, but they were also the friends who had the best relationships with their parents. When they use our names there's not this us vs them mentality. Yes, I'm their parent but I'm not superior. I earn my respect by respecting them, not by enforcing that I be referred to by some title. I don't need to hold a status above my kids.