Steve:  The logic of MAD is, as I noted, based on the "choice" to NOT precipitate the mass destructruction of your own nation.  It has "worked" since, though we and other nations have the nuclear capacity to destroy all live on the planet.  I'm guessing you read  "On the Beach" by Neville Shute or saw the 1959 film.  

Additionally, nuclear capability deters conventional warfare since it would be the end result of escalation.  If a nation, engaged in conventional warfare, perceived they were going to be totally defeated, the nuclear option...either battlefield level or targeting civilian populations becomes an "attractive" option.  

In many way, IMO, it would be "nice" to not have nuclear weapons, but I would suggest w/o them we'd be far more likely to have had more and more serious "conventional" wars.  Yes, MAD, is insane....but it may be less insane than what we'd face w/o it.  (cont)