ETA: There is now a third thread, so send new comments there.
Since the first thread has exceeded 500 comments, it seems time for a new one, with Eliezer's just-posted Chapter 33 & 34 to kick things off.
From previous post:
Spoiler Warning: this thread contains unrot13'd spoilers for Harry Potter and the Methods of Rationality up to the current chapter and for the original Harry Potter series. Please continue to use rot13 for spoilers to other works of fiction, or if you have insider knowledge of future chapters of Harry Potter and the Methods of Rationality.
A suggestion: mention at the top of your comment which chapter you're commenting on, or what chapter you're up to, so that people can understand the context of your comment even after more chapters have been posted. This can also help people avoid reading spoilers for a new chapter before they realize that there is a new chapter.
Even if we accept that creating conscious entities which are forced by means of their preferences to do menial work is wrong, it would seem to be better to create them, than to force those who don't enjoy such work to do it.
This is a bit of a false dichotomy - you don't have to force anyone to do it. Offer a sufficiently high salary to scrub Hogwarts' toilet (or just to cast Cleaning Charms on them), and voila, you have free-willed, willing, unmodified house workers.
The meaningful question (at least, to the degree that any moral question can be meaningful) is whether there is any value in that "unmodified" qualifier.
They still don't enjoy the work, even if they find doing it instrumentally rational. They are forced to do it by circumstances, and in a better world they wouldn't be.