I think you may be right. If you’ll recall, most of the classic Universal horror films were produced in the 1930’s and on into the war years. If any era had real reasons to be afraid, that was it. The weird thing about all this crap is that the threats come from everywhere and there is no solution but constant killing, vigilance and despair. Compare that to Frankenstein, Wolfman or Dracula who were single monster threats and could be reliably put down with a happy ending- at least until the studio could jinn up a reason to shoot a sequel.
The Walking Dead is somewhat of a special case, it is more of a western than a zombie movie. A western is about justice and morality when a character is trapped in an immoral situation with nothing to rely on but themselves and their own conscience.