The way I see it, having nukes gets you into the Secret Club of World Powers. The permanent members of the UN Security Council? The first six nations to have nukes.... In addition to having the weapons that make you a Force To Be Reckoned With, the whole development process requires a scientific and technological infrastructure that kind of means you have to be at least a mid-sized player on the global stage. The problem is that all these new countries who want nukes don't see the other side of the coin (or they just don't give a fuck) - any nation who uses one in anger will instantly become a pariah, even if they aren't immediately bombed into rubble in retaliation. So for most nations, it's simply not a worthwhile effort to get them. The global web of alliances and treaties built up in the post-WWII era has pretty much held.
It's only these rogue states that for whatever reason *can't* offer their people another way to the adult's table that are trying to get nukes, in the hopes they can bully their way into respectability.
Unfortunately, the President of the US is someone just like them....
We all (regardless of political affiliation) pray that it never comes to this, but in my sick imagination, I can hear someone crying, (clickit)