Justice and Rule
Legend
That is how I feel about the question vis a vis the Forgotten Realms, which is what you asked about.
But it's not the question. I'm trying to ask how important you think it is to the setting, regardless of "canon" or what not. I'm asking if slavery is integral to making the Realms work as a setting.
Forgotten Realms is a good example of what we lose due to censorship. Apparently, Ed Greenwood's original was heavy on the Free Love, and all those "festhalls" on the city maps were originally brothels/sex clubs, and people were overall very open about experimenting and trying new things, like Belts of Gender Change. We can only dream of the D&D that could have been if not for those uptight evangelicals, or concede that these changes probably were a good idea to create a marketable product.