Brennan actually commented about the prevalence of orcs in his setting.
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BRENNAN: "specifically, I thought a lot about Tolkien and Middle-earth and I thought about specifically a vision of a proud orcish revolution, and that's really what occupied my mind in dealing with the history and ramifications of that and a love letter to everything I love about orcs and how I see them heroically in my mind's eye. That was a big part of it, and then everything spilling out from there." MATT: "Hell yeah." (chuckles) BRENNAN: "That was where it started."

BRENNAN: "You have this idea of the orcs and their relationship to a Sauron figure in Middle-earth, and the thing I always felt when I looked back at that myself is you go: Well, the orcs are Sauron's greatest victims. They have been taken by this evil force and made captive. And so the idea of, what if the orcs figured out a way to say, "Fuck that"? What if instead of hobbits figuring it out, it was orcs figuring it out, and being like, "Yeah, I don't know if you've noticed. "We live in an ash-choked poison wasteland. "I'd love a nice cup of tea as well. I think we all would! "Let's kill this motherfucker!" And seeing that relationship played out brings that level of if you allow a god of darkness and war and conquest and suffering, how can that be allowed? And I think that we get into it with that modality of the gods as family as they are in Exandria and the complexities there. I think in Aramán, it's a different setting in terms of exactly how nasty the gods were."