The child still has a mother and father....obviously.
Life can be tangled enough on its own. You don't have to deliberately create a wad of legal, biological and relational knots, snippets, chopped-off bonds and tangles, exclude natural parents by contract, and say "Well, at least you're alive."
If a couple wants a kid and can't have them the normal way, they should adopt some kids. There are tens of thousands out there. We were lucky to get one. It's a real crime that the system makes it so hard to adopt.
Unless, of course, you're gay.