I think the main point is that it's considered unethical by today's standards because you interfere heavily with someone's life without them consenting. Sure,

I think the main point is that it's considered unethical by today's standards because you interfere heavily with someone's life without them consenting. Sure, now you say you wouldn't mind, but what if your life takes a bad turn and you blame one of the changes your parents made for that (if true or not)?