Since you introduce slavery how about getting sub plot going there, visit slave market maybe play some moral choice there, buy one, uplift them, buy one be cruel to them, or not interested at all, we have something like underground fighting ring and somewhat auction of relic and artifacts, it seems like missing opportunity for not introducing slave auction or market, I mean we only get one chance to do this during Sanziyan hunt, if we choose to teach those cultivator a lesson we can get a slave.
It seems like missed opportunity, the concept is there but not further explored, what's the scale of this slavery, how one can be come slave, how to buy freedom if such concept exists, so far MC only view the world from elite point of view, the lowest of MC's friend probably Li Hua since he is from merchant family, so far MC only meet couple characters that can be categorized as downtrodden.
not sure about song mao since he is not telling his past in detail just yet, Lu Yan despite being treated harshly by her family still among the elite group.