Hmm, I'd say that Civilization is more like heroin, you just sort of relax and enter an other-worldly state for hours on end, completely losing track of the world around you, but never really feeling in any danger.
Minecraft is the meth of gaming. It consumes your time in a similar way, but you're constantly on edge throughout the experience, you always feel like there's something behind you watching everything you do, waiting for the right moment to pounce. It also feeds the player's obsessive compulsive tendencies.
Man, good thing I never gave Minecraft a try.
(just noticed you started the Minecraft thread in Gaming as well ...the theory sustains!)