In the same way that I don't care about skin color; I also don't care about features continuing to exist and be diverse.
As mentioned, I recognize that we're in over our heads technically. I respect that if we were to "wipe something out" it very likely could end up a huge negative to humanity, due to unknown genes and etc.
However the discussion largely took a moral twist when racism/etc got brought up, and frankly I just don't care. I'm not one for history; so the moral implication of not having a physical-feature-group of humanity around, be it freckles, blue eyes, brown hair, light skinned, tall people or whatever, is entirely lost on me.
Humanity from my perspective seems far worse off having cared so much about our differences that I see little reason to be morally concerned about their absence. I imagine we would be better off for it, since we clearly fail with diversity now, it's not buying us any favors.
Likewise, with or without diversity, we will still certainly find reasons to hate each other. The conversation will just change. We're good at hate.
It might be worth reconsidering that viewpoint. As you say, we're good at hate. We've been good at it, too.
We've seen that something as simple as preferring male children to female children has dramatic societal consequences. It might be reasonable to decide you want to bias your child against being left-handed — lefties do have higher rates of accidents due to using right-handed tools after all. What might the societal shifts be as a result? Might we effectively loose some diversity of _thought_ and progress in our society at large? How might remaining lefties be perceived?
But if we're that worried about even something as minor as lefties, should we not release products either? How are people on phones all the time perceived? If I release a tanning product, should I be concerned about how tanning users are perceived? If I engineer kids with longer hair, am I concerned how they are perceived?
I think we run the risk of anything being hate-able, and thus nothing matters in that regard. Or at least, roughly speaking. Any big change has potentially huge and unknown societal consequences. I mean hell, people were freaking out about a McDonalds McNugget sauce a year ago over a TV Show. I'm not sure the worst of humanity is what we need to nix life saving medical procedures over.