My opinion is that the existence of surrogacy means that science is evolving, which is something that cannot be stopped.
Why do we have no objection with the fact that a woman gives a child for adoption and disagree with a woman that offers her womb to carry a baby for another person? Why do we see it normal that someone lives with the vital organ of someone else but do not accept that a woman carries a baby for someone else? I can understand that it causes an initial shock in our society. However, if it is treated with responsibility, based on ethical principles and lawfully, like in those countries where it is permitted, it should not be different or "worse" than donor conception or fertility treatments.
I think that, actually, it is a religious fear after all, generated from the idea that humans have the divine ability of creating life, and there are more detractors due to religious reasons than medical, social, or legal.
Obviously, abusive situations must be prevented, including mercantilism and reproductive exploitation, especially in underdeveloped countries, since we are talking about human dignity.