In the end, it all comes down to your goals and your audience!
Speaking only for myself, as someone who uses they/them, I’m happy with IF that wants you to inhabit a specific character (I’m not expecting to choose Sherlock Holmes’s gender), I’m happy with a male/female gender select, I’m happy with a male/female/nonbinary gender select, I’m happy with an “enter your own pronouns” gender select, I’m happy with “the game never refers to the player character’s gender at all”. The only one I don’t especially like is “the player character is specifically meant to be you, the player, but the author never considered that non-male people might play IF”.
Choice of Games has a very particular style where the player character is supposed to be as customizable as possible, which is why there’s so much discussion of custom pronouns. But outside of CoG, I’m not going to be offended or anything if an author doesn’t provide that option, or doesn’t provide a nonbinary option at all. Rewriting Inform’s standard library to support singular “they” doesn’t need to be the author’s highest priority.[1]
It all comes down to the needs of the particular story, imo. It’s always nice to feel represented, but representation isn’t the only thing that matters. I won’t be taking any points off my IFComp rating if a game only provides male and female options with no they/them support.
Though now there’s a solid extension for it, which is great—I spent way, way too long trying to make it work in Scroll Thief and it still had bugs in the edge cases, and that’s not even getting into entirely custom pronouns! ↩︎