Is it just the fact that the world-building included this at all, or that you didn't feel the narrative explicitly enough condemned that caste system/slavery stuff? (I haven't read the good so am curious before I read, I guess...). I can understand maybe having it in world building if it is being used to discuss or condemn a topic, like the stuff in 1984 or Brave New World. On the other hand, it is disappointing if it did not come off that way...

Hope you enjoy Persuasion; it is my favorite work of Austen's (perhaps because I am now older too?)