For some reason, I'm slightly scared of discussions so I pondered for a long time whether to participate in this thread but this post has been skulking about my mind for several days now so... here.
I'm definitely for more of them. To me, it's less a question of "why?" than one of "why not?".
I don't want to repeat (too much) of what I've read has already been said, only that:
In addition to representation by including characters of different orientations/genders/otherIdentityAspects, making people more aware of the fact that there are lots of people whose idea of happiness might look slightly different from their own would be nice.
Personal example: I'm kind of dreaming of the day when, after I had to, for some reason, reiterate that I'm not interested in anyone romantically (aro/ace seems the label that describes me best), that person simply shrugs an "okay", instead of getting that (to me) annoying look of sympathy in their eyes, stating "Oooh, the Right One will wait for you somewhere don't worry I'm sure of it", simply because they've never encountered someone like that in life or media before. .__."
My own characters and world building reflect my want of more of such characters.
It's not what defines the characters as their One Defining Trait (that'd be boring, among other things), usually isn't even obvious from moment 1, but it may come up in party banter, or during that awkward moment when the party learns that a party members' exes have named their firstborn child after him, simply because it's part of them and their lives.
I also create my settings generally (generally because there always will be people with different opinions no matter the culture they grew up in) so it's not that big of a deal to be a LGBTA+AllTheLettersI'veForgottenOrDidn'tKnowAbout person there and it could still lead to interesting stories/side stories/backstories for people on that ... is spectrum the right word?, despite it being considered "normal" there. Plus, I can imagine that, for example, being a transman wanting to transition isn't a walk in the park even if he wouldn't get negative responses to it from a culture-wide point of view. Especially if he had to think about this while at the same time keeping his best friend out of trouble, studying for exams, and saving the world. Even more so if he's from a family of seafarers, the only heir, and there's a strong, cultural belief that letting men on ships invites bad luck (just think of the quest potential! He'd have to talk to people and search old archives to find out an accepted way to ward off bad luck if he has to leave the place by sea for example, and I should really stop expanding on that example before I end up with another project vying for my attention).
I feel like I can't really express what I'm trying to say right now, it's just... Those are people, and they might be different in several aspects from me, and I like putting different people in stories. Including those that happen to be on another "spot" than I am on the orientation/gender/etc. identity multidimensional... object..., so I used a lot of words to say that I'm comfortable with such characters, want more of them and that I'm inexperienced in trying to state a point.
Okay self, close your eyes and press Submit Reply, and stop worrying that you've forgotten anything.
Also, I'm sorry if I mixed up terms.