The switch from consquentialist language ("4D histories which include… are dispreferred") to deontological language ("…the degree to which we feel morally obligated to create more people") is confusing. I agree that saving the lives of existing people is a stronger moral imperative than creating new ones, at the level of deontological rules and virtuous conduct which is a large part of everyday human moral reasoning. I am much less clear than when evaluating 4D histories I assign higher utility to one with few people living long lives than to one with more people living shorter lives. Actually, I tend towards the opposite intuition preferring a world with more people who live less (as long as the their lives are still well worth living, etc.)