Imagine saying this about non-whites or, indeed, homosexuals.
You win today's Egocentricity Badge! Congratulations!
There is a difference, that it difference is that ethnic diversity (especially in a game with stylized characters like these) is a trivial inclusion and happens as a natural result of designing the characters, and sexuality diversity is a simple matter as well.
But "We need to do all the extra work required to represent disabled people/dwarves/amputees/people with vitiligo/burn victims/anorexics/bodybuilders/left-handedness" is an extra on top of the basics like "multiple skin tones".
Representing gay characters for the sheer sake of it is included in my argument. Representing black characters for the sheer sake of it is included in my argument. In a game where neither of those are necessary for the plot or world, no, excluding them is not a problem, and including them purely to fill a diversity quota is a stupid idea.
Pokemon Red, Blue, and Yellow feature not a single sprite that doesn't have a pale skintone. And does it matter? No, absolutely not, it does not. The games are set in a japan-like expy and everyone is presumably japanese. There is no necessity to represent anyone else, the game's value does not change based on whether or not they do, the plot has not a single thing to do with any character's race, and there's no need to fill a quota for the sake of it. That game world is not worse, offensive, or insensitive for not having characters with different sprite colors.
Plenty of RPGs with romance mechanics don't feature gay options. Does that bug me? Yes. Are the developers obligated to include them for the sake of fulfilling a diversity quota? Abso-freaking-lutely not, no, they are not. It's their story and if none of the characters are written as gay, that's how it goes, big whoop. If it's set in a space environment where all races have melded into one, sure. If it's set in space detroit where all charactesr are black, whatever.
You do NOT need one of everybody represented in anything, ever. It is not, nor should it be, a necessity. No developer, writer, artist of any kind should ever be shamed or pressured to emphasize inclusion or diversity simply "because". representation is very important, it is very powerful, and I am a huge fan of it particularly when it comes to homosexuality because my experience with homosexuality and learning that I was gay and what gay was and that it was just a thing and not a big deal all comes from my male sims being able to kiss in The Sims 1 (a game in a genre where sexual diversity is actually important, simply by design). But no, not every game needs a diversity quota and to fill it at the whims of anyone who asks. No person has a right to representation in any media. You just don't.
Also, I'm gay. So. Uh. Egocentric. Sure. Go straight people, only real people! Yeah, that's totally where I'm coming from.