"Because we can observe natural selection operating in a population does not mean those same selection processes should be applied, or are acceptable, to a human population."
Quite so, and said with the advantage of hindsight. Could you make this moral assertion with confidence, absent taboos adopted due to the hellish abyss created by scientists working for the Nazi regime?
If I viewed just as an improvement to humans, probably not.
Fortunately for my decision making process, eugenic style improvement carries with it a lot of other moral baggage that would encourage me to make the same judgment call and reject eugenics.