>Overall, this is a good thing - I certainly don't want to go back to superstition, subsistence farming, and dying of infectious diseases at 50.

A nitpick but people weren't dying at 50; they were dying as infants. The average life expectancy was around 50 because so many children died, but the life expectancy of people who made it past age 5 was around 60-70: https://pmc.ncbi.nlm.nih.gov/articles/PMC2625386/ .