Maybe because, as an autistic, my morality is rather pragmatic- John Paul II's Theology of the Body makes sense to me precisely *because* it fits in with evolution and survival of the species. Respect for human life between conception and natural death also fits in strongly with the liberal neurodiversity side of things; a mutation that might be seen as negative in one light (like sickle cell anemia and the lessened ability to process and use oxygen) can be positive in another light (immunity to malaria); and at first glance we human beings just don't have the intelligence to know the difference.
If, as theistic Intelligent Designers claim, God created evolution and it's his method of engineering, then reducing the genetic diversity of the species is indeed taking the power of life and death, the central power of evolution, out of the hands of God and giving it to man. And based on our inability to know long term good from evil with mutations that are normal to the human species, yes, that becomes a moral argument.