One of the more interesting ones I've heard is to separate ourselves from animals. This is actually a religious argument going back to humans being permitted meat after the flood. What was the reasoning? To help humans mentally separate themselves from animals.

You do sometimes see vegans being kind of anti-human, pro human extinction. And I think that's one of the things that this (very old fashioned) argument is cautioning against.

I'd say that most people, and certainly most omnivores, see humans as more important than animals. And when you see vegans celebrating the deaths of hunters etc, you're seeing a strong conflict with a human focused moral code. And you don't really see that among non-vegans as much. I don't know that this mindset is something that vegans typically see as problematic, but omnivores definitely do.

Of course, this sort of argument does absolutely nothing to justify the amount of meat that your standard omnivore eats. Eating a little bit of meat during festive occasions and eating plant based the rest of the time would totally satisfy this.