If you go the "Eugenics was racist..." route you're going to be met with the "but what if we do non-racist eugenics.."
Or we can just nip the whole thing because failure and racist failure are both just failure.
how about eugenics is immoral because every human being deserves to live and reproduce.
We give genetic testing to every person for free at a few of their regular checkups with their primary care doctor.
If you test positive for some genetic markers, you get free IVF, paid for by the government. If you have some kind of anti-IVF bent, it's not mandatory, just a benefit you aren't using. The IVF process picks embryos that have the least undesirable traits - but you will definitely have a kid and it will be yours.
You have eugenics and no forced sterilization, no murdering people, nothing.
It still won't work, but you have ethical eugenics.
Wait - you think the problem with eugenics is that it was ineffective? I think we need to talk a lot more about eugenics.