It sounds trashy, sleazy and ignorant to me.
Ignorant about what?
I think it sounds ignorant because it's grammatically incorrect. It's just one of those phrases that makes me cringe a bit.
As another poster mentioned, if you're going to use the phrase at all it should include an 's (my baby's daddy).
It also sounds odd (to me) to say "daddy" rather than "father" (or at least "dad") when speaking to another adult. For example, I might say, "Your daddy will be here soon" to a two year old, but if I was speaking to an adult I would say, "My son's father will be here soon."
ignorant meaning rude or uneducatedIgnorant about what?
It sounds ignorant to me. It does not convey the sense of a respectful relationship and I feel sorry for the children hearing their parents referred to in this manner.
I guess I'm old too, but it also makes me grit my teeth when a man or couple says "we're pregnant". No, only the woman can be pregnant.
To the bolded that phrase doesn't really make me grit my teeth so much as just think to myself "if WE'RE pregnant then how about you take morning sickness and trips to the bathroom every 20 minutes this week." lol.
I have heard it used not just towards a person's ex but also towards their own significant other.
I don't think that's necessarily true. I do use the term. My niece has a "baby daddy". He dumped my dsil a year after she was born, said my sil had gotten fat and grossed him out (he's a gem!!). lives not 7miles away, doesn't see his daughter no help out.That the speaker is not very intelligent.
It conjures up negative images for me. I don't use it. I makes me sad that people are so callous when it comes to bringing children into this world.
It might be more mainstream, but that doesn't make it positive. Would you apply for a job or college scholarship and say "here is a letter of recommendation from my babydaddy and another from my homie"?