This is going to be a fraught post and I'm not sure I'll articulate everything I mean to clearly. That's not meant as a shield, it's just the truth. I'll try my best though. I know I have a very patient audience.
I mean, for one thing, we can start optimistically. There's lots of great fantasy fiction that's humans-only! A Song of Ice and Fire, Conan the Barbarian and most other Sword & Sorcery, Arthurian Mythology, most other real-world mythologies, most fairy tales and fairy tale-inspired fiction (e.g. Alice in Wonderland and Peter Pan and whatnot), most gothic fantasy/horror (e.g. Dracula), most pirate-y fiction, and so on. And others are human-centric to the point that things which may be called "dwarves" or "goblins" or whatever else are either clearly not societies or they're so peripheral to the action that "playing as one" wouldn't make much sense at all. Hellboy, Dark Souls, Darkest Dungeon, et cetera.
So if anything, it's really the default option, right? Elves and dwarves are the exception. Everyone should be asked to justify why they are including non-human player options, rather than me being asked why I'm not.
But here I am. I need to explain myself and it's going to be messy. If you're getting used to hearing arguments about orcs and dark elves a lot lately, this post is about that. I've been sitting on this post for a while now. This is going to take me a while to explain my line of thinking but please bear with me. There is a reason for each section in this post.