And? How does including such things in D&D affect those people? Should the creators of D&D products try to avoid any topics that might trigger something negative in anyone who might read it?
How about if the creators of D&D products simply don't include something that noxious in their games in the first place?
You don't need to worry about something that "might trigger something negative." You could simply use some basic decency to know not to include things like that in a fantasy game that's supposed to be fun for everyone.
Lots of people have been "bled dry" by "vampires." Lots of people face "dragons" and "axe-wielding goblins." It is clothed in fiction, in mythic forms, but they can relate to anyone's experience.
Name one person who has literally be killed by a fire-breathing dragon, or has been turned into an undead, or has been attacked by an actual goblin.
I'm not looking for metaphors here. I want to see the actual cases.
Because the origin of muls
isn't a metaphor in-game.
Or is it the literal nature of slavery, of breeding that you find problematic? And therefore, must D&D fantasy be completely mythic, with no connection to history whatsoever?
What about war veterans, most with some degree of combat-related PTSD?
When you play D&D, you know you're going into a game involving combat and fantasy violence. "May include sex slavery" isn't one of those things D&D is known for. Nor should it be.
To the best of my knowledge, D&D hasn't included torture instruments in their equipment lists. I mean, I know that whips are weapons, but I certainly can't recall them putting a gp value on The Rack or The Pear or The Iron Maiden. Does the lack of official torture instruments bother you? D&D also doesn't generally include rules for things like syphilis or cancer (the odd prestige class notwithstanding). Does this make you think that D&D is going out of their way to "avoid triggering people"? Do that also make you think they're following "unreasonable restrictions as to what can be published"?
If not, then why is it so important that they include sex slavery?
Muls are a rare instance of something being "carved in stone" in such a way. But if a person doesn't want that back-story they don't have to play a mul. Or if they want to, the DM can accommodate that. And of course, not everyone has to play Dark Sun! Should it, then, not exist, except in a format that removes any possible triggers?
Or, you can do the simple thing and
change the origin of the muls. After all,
no other species in D&D is created solely by forced-breeding for the purpose of creating slaves. Even when orcs were at their worst, it was never assumed that half-orcs were
only the result of rape.
Have you ever heard of exposure therapy? It has been used to generally good results with war veterans and other trauma survivors. The basic idea is exposing them to a small dose of what traumatized them, be it through memory or virtual reality. This is not to say that D&D should be a therapeutic environment, but I bring this up to point out that encountering such things in the safe context of a fantasy game with friends may actually be beneficial.
Aaaand here's where I'm done with you.
Exposure therapy, like all forms of therapy, require
consent on the part of the patient. The person has to
agree to be exposed to the thing that traumatized them,
and the person who is administering the therapy has to be an actual therapist who knows what they're doing.
A DM is
not a therapist. And the player isn't consenting to therapy; they're playing a game.
And not everyone who doesn't want sex slavery in a game has been traumatized in some way. I've never been sexually assaulted or abused. I don't want sex slavery in my game.