I don't get it.
In 40 years of playing D&D I can never remember any characters with any kind of sexual preference.
I have never played a heterosexual character, I have never played a bisexual character, I have never played a homosexual character, I have never played a cisgender character, I have never played a transgender character. For the most part I have not DMed characters that fall into those buckets, labels and stereotypes, nor can I remember other players with such characters.
This is not a "thing" in the games I play and essentially every character I have ever played has been asexual with no defined sexual preference. To date, they have all had an identified a gender. So not binary, but not necessarily cisgender either. There were male characters and female characters, but I never put any effort into making them cis or trans and to be honest I don't know what the difference would be if I did. How is a cisgender Tiefling woman different than a transgender Tiefling woman. They are a female Tiefling regardless! To be clear I have played female characters with beards (mostly dwarves), and men who could not grow facial hair (mostly elves). I have played weak and small men, strong and huge women and vice versa. Were they cis or trans? I have no idea and I was the one who created and played them!
I just don't understand what exactly this is about and what exactly an "LGBTQIA+ setting" is as my games, including games in all published settings have been this way from the beginning.
Now if this is talking about discrimination against certain players, that is an entirely different story, but if we are talking about the game world and characters in the game, I do not understand what it means or what it is supposed to mean.
Others have responded to this already, but I wanted to add my two cents, even though the thread has moved beyond it a bit. Of course everyone's playing style is going to be different, but many people enjoy relationships in RPGs, whether that is platonic or romantic. They also like fleshing out their characters, and that usually includes the gender of said character. I'm not judging your gaming style, but it
does come up for others. I'm asexual, but I still form deep platonic bonds, and my characters often have relationships. I understand that some players don't go in to this kind of thing, but others do, and WotC is finally seeing that those relationships may not be the "default".
Or it can even be something as simple as going to an inn that is run by the innkeeper and
his husband, rather than the "default" heterosexual relationship. It can be part of the worldbuilding without being central. And, as others have mentioned, while players and DMs have always played how they want, having the acknowledgement that lgbtq+ people can and should exist in fantasy settings, just as they do in the real world, by having NPCs that are diverse in gender and sexual orientation, is a step forward in helping the queer community feel seen. Regardless of what you do in your home game, having representation in gaming material is important. And it's not (or shouldn't be) "Bob is gay, look how gay Bob is. He's a paladin of Torm, and is so gay." It's not about emphasizing the orientation of an NPC. Rather, it's "Bob is a paladin of Torm, and he journeys with his husband/boyfriend Fred, aiding those in need." You're not placing emphasis on his homosexuality, what you're doing is presenting him as a person, the same way you would the "default" heterosexual paladin (to continue using paladin as an example). Because cis het has been the assumed for so long, having characters that are not is important. And it's not about listing their orientation, it's about showing it, such as in the example I gave above.
Just as in non gaming fantasy books, whether romance is a big theme in the books or not, there is usually a boy-meets-girl scenario. Thus, the assumed identity is cis-het. But by making it a boy-meets-boy or girl-meets-girl, or a nonbinary character, you are showing readers (the world, really), that they are people, too, and can have adventures and slay dragons the same as the "default" cis-het characters have.