I do judge Plato as a racist advocate of propaganda, and as Popper put it 'enemy of the open society'.
Dawkins recently tripped up over a very similar attitude to the word eugenics that you are showing. He attempted to use the term eugenics to mean any strategic non individually decided influence on reproduction. But that's not how the term is used. It invariably implies coercion. So the moral arguments are the same as apply to any other kind of coercion by a group or state against an individual's interests or choice, ie it would have to be for morally consistent reasons, to be moral. If coercion is not involved, it's just the niche we are adapting to changing, and that's not eugenics.
Dawkins attempted to distinguish between 'negative' and 'positive' eugenics, ie between sterilising deaf people and encouraging the 'master' race to breed more. It did not go well.
Fundamentally, humans are not primarily conditioned by our genes. They certainly impact averages, and we can certainly find causal relationships to niche phenomena. But what is uniquely human, is our hugely extended development period. We are defenceless far long as a fraction of lifespan and in absolute terms than any other animal. Our neocortex, which chiefly governs impulse inhibition, is not fully developed until about age 25. Our adaptability as a species is all about culture meeting malleable brains. The film Gattaca is a superb consideration of the issues.
Another canard. The increase in global resource use by the top consuming ten percent, outpaces the increase from population growth of the poorest 50%. 'Overproduction' is about organisation, not resources. See China's amazing coastal aquaculture for instance, which produces 10% of their calories.
The birthrate is now at or below replacement in every region except Subsaharan Africa. The reasons for such demographic transitions are both obvious and extremely well studied, and give the lie to your "randomly" (which puts me in mind of Churchill justifying causing the Bengal famine because "they breed like rabbits"). Whenever there is access to healthcare especially antenatal care but also vaccines, education for women, and access to contraception, the human strategy switches from large families in the hope some will survive, to small families with largest possible investment of resources in fewer children.
Also, and this becomes a moral argument against, consider how much we don't know. Cloning causes health abnormalities we can't currently fully explain, or prevent. The number of genes humans have is remarkably small, and as I understand it given hominids fused two ape chromosomes, we actually have less genes than chimpanzees. Genes are each enormously complex multifaceted tools, and we know selection pressures on animals cause health side effects. Humans are also exceptionally genetically similar, because of the population bottleneck to below 10,000, possibly below 1,000, linked to an eruption 70,000 years ago. There is less genetic variation in all humans, than within some breeds of dog. It should also be noted that genes have been highly mobile, like the spread of lactose tolerance. Genes with clear advantages don't need help, and spread between populations.
Lastly: "unusually shrouded in taboo"
You are on course with your use of words in your post, to make yourself the enemy of all right-thinking people. Don't use the word eugenics casually or fuzzily, it carries the weight of the greatest crime in human history with it. Your lazy inferences about "randomly overproducing" link directly to the so ridiculously totally discredited racist thinking of Malthus. You sound a step away from outing yourself as full-blown sterilise-the-disabled racist. I can't think of a better taboo to have than against that.
EDITED TO ADD:
There is a game-theoretic argument against eugenics. It's the same argument that applies against 'pure' group selection in genetics, and required it be reformulated as multi-level selection. Basically, because the unit of selection is genes, whenever a group entity tries to act consistently against the interests of a significant fraction of individuals, it incentivises the creation of a free-rider problem, non-contributing extractors, shielded from selection. This has been a problem for absolute monarchies and unrestricted aristocracies, and autocratic states everywhere, making them less creative and efficient than voluntarily cooperative groups, and selecting for an out-of-touch elite who become increasingly unable to adapt to change.