While normally I wholeheartedly agree with everything you post, I think there's a bit of perspective lost here. Everyone has their own playstyle, and especially for a game like Terraria where there is no set protagonist... well. You create your own avatar from whole cloth. They have no professed personality
to compare or contrast yourself with. Some people like to create characters and build their own stories as they traverse the world. Some people like to copy other characters and roleplay as them. Some people like to build themselves and play as their avatar. And some people just don't pay any attention to this aspect at all. It's not usually a deliberate choice.
Point is, the less fleshed out a protagonist is, the more room there is for the player to project themselves onto them, and Terraria's is a complete blank slate. So even if that isn't how you play, many people use chargen as an opportunity to make themselves, and I can see why people would ask for ways to make that character closer to what they want it to be. And it's not a knock against anyone's creativity if that's how they default to playing a game.
That said...
If the option does literally nothing to change how the character looks or sounds, then I don't see why people can't just select male or female and then just envision their character as nonbinary. While nb options are growing more common, especially in indie games, this is what has to be done in maybe 95% of game situations anyway. It's the same flexibility of imagination that lets you do... well, anything that isn't explicitly codified in the game itself. Playing Terraria and saying 'my character is nonbinary' is the same leap of logic as saying 'my character was an ordinary teenager and woke up in Terraria one day with no idea how he got there', 'my character is the girlfriend of the Steampunker', or 'my character is the prophesied guardian of the planet and the only thing the Corruption fears.'
And that's partly because a vanishingly low percentage of people are actually hermaphroditic. Gender is a mental attribute, not a physical one. I don't want to get into semantics or present the idea that I'm knocking the validity of gender identity in any way - it's immensely well-documented that gender identity doesn't always line up with biological sex, and it's nobody else's business how people choose to see themselves. If you feel dysphoric about your birth sex, nobody should force you into that role; if you don't identify with either sex, give me some pronouns and I'll use them. But... Maybe I'm just speaking as someone who's never struggled with this, but when I look at the ability to make a character nonbinary, I view it from the same vantage as making a character trans, or lesbian, or shy, or an avid collector of plush rabbits. It's a who, not a what - a character trait, and Terraria has none of those whatsoever. No venue for expression of them, no room for them to affect gameplay. So bringing it up at all is more of an inclusivity thing than anything that actually expands or adds to the game, and sometimes that's worthwhile anyway - but then it's a pure cost/effectiveness thing.
It's like... consider that Terraria has skin sliders, and if it didn't and the game generated every character with the same pale peach skintone, I'd be advocating for increased customization with everyone else. But the nice thing about the skin sliders is that they're a catch-all - they grant
everyone the exact same freedom of self-insertion (and wild unrealistic customisation) without requiring catering to a specific group (which means you have to provide that same accessibility to everyone.) Imagine the infinitely generating mess if instead of an RBG skin slider, you had a swap list of ethnic features you could add onto the character.
A nonbinary gender option is also a catch-all, at least in theory, but the problem is twofold - it's catering to a much smaller group of people, and it isn't adding a new field, it's altering an existing one which was already designed to work a certain way. Worse, it's a field that's widely referenced. Skintone affects the player sprite and nothing else. Off the top of my head, gender affects the player sprite, hit sounds, the appearance of most armor, vanity, and accessories, and NPC dialogue.
Even if the option was a dummy, it would potentially cause problems for how the game accesses character gender just by existing. Depending on the way Terraria is built, it either adds a clause to any gender reference (which is fine) or requires the entire system to be rewritten.
It's
doable, especially if you don't expect a new character model*, but nonbinaries aren't a particularly large group, and the number of nbs who look at a male/female character select screen and become genuinely distressed instead of picking a sex and just envisioning the character as nonbinary is much, much smaller - people with serious stigmas about biological sex. I just don't think there's enough of a demand to merit this for what it would take to implement at this stage.
*I'd think that's an even bigger can of worms, honestly. Throwing the gates wide open for height, weight, and musculature options, and after a nonbinary option, they're difficult to argue against through the lens of inclusivity because they're offering representation to a much wider number of people. The problem with prioritizing things like this is that there's really no empirical way to measure what part of someone's identity is important to them, or what portion of everyone who checks a box cares strongly about the check in that box.
up some points.