If religion or politics were the crux of the argument against the costumes of the elves, then these would have been mentioned.
Personally, I'm atheist, but I'm not sure what difference that makes. We can debate religion on another forum.
It may surprise you to learn that people on the "left" (eg feminists) are not a homogenous group. While making posts in this forum supporting feminist ideals, I've also made posts in other venues in opposition to so-called feminism. For every feminist you meet, there's another feminist with a different interpretation of what feminism means. So you can never completely please everyone. I have personal experience dealing with the extreme fringes of feminism.
But most people are rational and if we sit together and discuss the issue in a mature way, we can start understanding each other and potentially find common ground.
Anyway, I don't see the elf designs as deliberately sexist, but I think with Sebille as the only elf character (and the first character you see) it looks sexist, and that's not a good thing.
My main concern is that the designs are impractical, unnecessary and jarringly inconsistent with the equipment you're outfitting them with.
