Sorry, but this is just pure "Gell-Mann amnesia effect" vibe to me. I mean, you've just brought up a perfect example yourself! What kind of mental gymnastics does it take to still hope that this time it's not like that?
I don't wanna start the whole "vaccines cause autism" thing and whatnot, and surely you shouldn't avoid ultrasound just because of irrational fear of some yet undiscovered side-effects, but it's really amazing, how people tell fun stories about how common was the narrative about major war being very unlikely in "modern days" (because who would dare to do that with this kind of technology!) right before WW1, and then conclude with firmly believing that these days (after WW2) it sure won't happen, because humans are not that dumb. And my point is, that perhaps it indeed might have been a bit less likely, if people didn't believe that it is so unlikely to keep stepping on the same rake.