Threads was created with the specific purpose to be existential dread inducing nightmare fuel, a nuclear deterrent and a documentary all at once. I see it as the most horrific movie ever made. To a fault. It is so successful in achieving its goals it makes you question whether you can enjoy it. I admire its formal qualities and cinematic language, but every time I know I'm admiring the spectacle of human suffering.

I guess you can't separate that from "good" horror. Threads has both visceral horror and heaps of implicit philosophical horror. So yeah, watch it if you want to stare at the void.