There are now more actors with nuclear weapons and the means to deliver them. Did you know that India has built two ssbns? (nuclear subs armed with balistic nuclear tipped missiles). North Korea has h bombs and ibcms, Pakistan has a bunch of fission bombs.

Worse who would disagree with the premise that the governance of nuclear armed states has deteriorated? China has a president for life, Russia wishes its president for life would live forever - because God alone knows what will crawl out and take over when putin goes (and if you think the Russians should be worried, the Germans should be hysterical about this but aren't which scares me much) and trump and brexit are bad signs too.

Also people seem to low ball the effect of a nuclear conflict or the media on a regular basis. Make no mistake, we are half an hour from 300m deaths. And that will be just the down payment.

edited - I meant to type fission but typed fussion.