Belen
Hero
Except I do not believe that anyone is arguing for graphic depictions. I would not support graphic depictions; however, evil beings will most likely use it if only as a way to increase power and I think it is fine to acknowledge it.Hierarchy of needs vs harm I would guess. While most of the playerbase doesn't care less, there are demographics that are traditionally underrepresented amongst D&D players for which it could be unpleasant or even traumatic.
The numbers of people who would find graphic depictions of slavery enough of a turn-off to not play the game are probably higher than the numbers of those who would find graphic depictions of slavery enough of a turn-on that they insist on its inclusion.
The former are probably more the target audience that WotC are aiming D&D at rather than the latter as well.
My current campaigns has a group of slavers from outside the region raiding villages. The people of the region would never allow the practice so the characters are on a quest to save the villagers.
The pirate slavers will be early antagonists for the region and slavery will not move beyond there unless the characters decide to leave the region to do something about the external threat.