The whole premise on this issue is that there is some enemy with its finger on the trigger just itching to pull it. But were it not for the Glorious Counter Threat of Our Government we would have been blasted by now. These assumptions are normally not accurate, but I can not rule out the possibility of both of these being true.
My logic why nukes are not useful is simply this: Nukes are expensive as are the delivery systems. They consume precious resources that could be used elsewhere. Then when created they must be carefully maintained. All of this is expensive. Our "enemies" typically are not that wealthy, because if they were then we would be trading partners and not pushing eachother around with defensive weapons.
For example: Would the Soviet Union of Misery, Violence and Poverty still exist with its borders intact if it did not engage the West in the Cold War?
So the real reason that "enemies" build nukes is that they are protecting themselves from agression. Ie, US.
ICBMs are expensive delivery systems to build and to maintain, but a yacht sailed into a harbour is not. The later would be my guess for the most likely mode of attack in the next ten years.
I came across an interesting bit of information the other day--the rockets used to launch nukes are about 95% identitical to those used to launch rockets into outerspace. The knowledge and technology needed to gain control of outer space (which was an objective on both sides, and according to the Project for a New American Century, still is for American neo-conservatives) was developed in part by building and testing nukes. Space dominance is important for an imperial power of course, because it would allow a nation to control uses of satellities and therefore, communication. This is just part of the reason for the accumulation of U.S. and Soviet weapons in the 20th century, but the fact that we owned them raised the desire for others to as well in order to protect themselves from us.
Yes, the space and nuclear programs are very expensive, but it is my understanding that the collapse of the Soviet Union was due to the failure of its political and economic structure. If they hadn't spent all that money on the Cold War, it would have taken longer perhaps to fall, but essentially I think it was that the failure of socialism in such a large nation was bound to happen.