Michael, you're certainly right that the broader point stands. We should expect a real utopia initially to horrify us in some of its particulars (that said, many famous literary utopias pass this test with ease - horror is a necessary but entirely insufficient criterion, apparently). It nonetheless seems blithe to assert that our world's 'improvement' fully explains Franklin's hypothesized disgust. The improvements that seem least ambiguous, such as vaccines, would be those least likely to disgust him.