BTW, MAD may not be the exclusive purpose of nukes in today's interesting political and military climate. Some of you may recall that in the run up to the first Iraq war, Hussein was threatening to use chemical weapons against any allied troops that attacked his country. Although no WMD's (meaning nukes) were found per se, Iraq did have (and used on Kurds) chemical munitions.
Diplomatic contacts were engaged with Hussein and his military, sending the message that if Hussein deployed chemical weapons, the US would respond with nuclear weapons. According to intelligence at the time, Iraq decided not to risk the nuclear response option and did not use chemical weapons in theater.
So to some extent, the threat of use, coupled with the real ability to do so, may have had some strategic and tactical effect in a more confined conflict.