It's only objectively better until another world war comes - we are not immune, and then, it will be easily objectively worse. This argument is rather pointless - externalizing warfare to poor nations and then saying the world is "peaceful" is quite immoral.
Espionage is not used by governments to maintain peace and reduce war fatalities - it's used by governments to gain an edge over their adversaries. Espionage existed in WW2 as it did in times of peace - to say peace is a consequence of it is absurd.
MAD is the only thing that has prevented major world conflict.