Eugenics in principle is brilliant and necessary.
Quoting: MissCleo Eugenics is a dirty word to many people, by virtue of those who advocated for it in the past.
The principle is nothing more than the improvement or tailoring of a species through a process of selective breeding over many generations. All domesticated species that have been used for food or work over countless millenia have been subjected to this process, as have plants used for food or products. Nobody seems to have an issue when these species are tailored over generations, favoring some traits above others.
The issue seems to be when we start talking about doing the same thing with human beings. You're basically deciding that one couple's great-great-great grandkids are going to be academics, scientists, inventors, composers - and another couple's are going to be gas-station attendants and janitors.
And ideally, they are all going to be healthy and productive to a ripe old age and then die suddenly so there is no long-term drain on the system.
Frankly while eugenics may have been a great idea if practiced since the 1800's, it's likely of limited utility these days. Most of the working populace will be made obsolete by technology within the next 40-50 years. It's entirely possible that even the advanced professions will be surpassed by automated intelligent systems by then too.
Genetic therapy may help the human race faster and in a more efficient manner than eugenics at this point. And may, to an extent, allow an individual to decide for themself what traits they want to possess. But to what end? If all the important functions in society are performed by AI and robotics, who cares how smart, or strong, or productive you are capable of being?
It's a lot easier to come up with the "how" than the "why".