People who are already alive are biased - of course they'd want to maintain the status quo. You cannot ask children whether they want to be born before that happens.
All in all, I do think it is rather pointless to argue from the potential child's point of view.
From the point of view of the surrounding society, I would much rather have women become single mothers on purpose than have children with a wholly unfit man, and then end up single mothers who have to cope with a horrid ex on top of single parenting.
Germany suffers from a shrinking population due to a low number of births, so much that the idiots from the political right want to ban abortion to increase the number of births, and I think in that situation, it would really be preferrable to implement proper legislation for sperm donor babies. Like, state pays child support, sperm donor neither has to pay money nor gets to sue for custody.
It is not perfect for those children, but then, whose life is? Of course children should be able to find out who their biological parents are (in fact, it should be known to the mother, anyway, because inherited diseases, etc.), but I don't think the demand for a traditional two-parent family is reasonable.