I thought the Workers were another part of the unevenness of the book - they seemed at first like a sidestep to allow the thought-experiment aspect to proceed (ie part of the whole don't-bother-about-the-detail-this-is-a-fable), but then swung right away from that into SF. I did like the image of the streets paved with Socratic dialogues very much, though. (Hhmmm... I'm thinking now that it was that image which triggered the author to put in the whole sentience/slavery section.) But once it took the SF turn, the weakness of the worldbuilding and the characters stood out drastically - what tasks did the Workers actually do, once the city was built? what did the Children designated as Iron do at that stage, besides herding goats (and childcare? was that an Iron responsibility?)

It's not just the reader's unanswered questions - as you point out, the characters are weirdly incurious about all sorts of things. (Like which baby came from which parents, for starters - or why, after the concealed infanticides, the number of babies didn't match the number of births. You'd think at least Simmea would have noticed, with her penchant for statistics.)

and I agree with you to about their odd docility re: lack of sexual choice (as well as in so much more) - and also about the chanciness of the Ikaros/Maia/Klio business. There would surely have been rumours and resentment and probably huge rifts.

You say: "completely screws up the subject of rape, revenge, and forgiveness." Interesting - the author does attempt those then? Not so much revenge, which is horribly easy to write/attempt, but to work out how forgiveness happens - that's intriguing! (even if screwed up.)