2) Honestly, I would have been happy with the aliens' deal (even before it was implemented), and I think there is a ~60% chance that Elizier agrees.

I'm of the opinion that pain is a bad thing, except insofar as it prevents you from damaging yourself. People argue that pain is necessary to provide contrast to happiness, and that pleasure wouldn't be meaningful without pain, but I would say that boredom and slight discomfort provide more than enough contrast.

However, this future society disagrees. The idea that "pain is important" is ingrained in these people's minds, in much the same way that "rape is bad" is ingrained in ours. I think one of the main points Elizier is trying to make is that we would disagree with future humans almost as much as we would disagree with the baby-eaters or superhappies.

(Edit 1.5 years later: I was exaggerating in that second paragraph. I suspect I was trying too hard to sound insightful. The claims may or may not have merit, but I would no longer word them as forcefully.)