Yeah, but why should a government do so?
I've really no idea, but that's not the point. The risk was bad enough during the cold war when there were just a handful of countries involved; one out of ten or twenty or whatver is less of a problem than one out of a hundred or so.
Yes, but it's still possible. And more likely with a lot of countries having nukes to play with than just a handful.
That's very true, but that doesn't mean that at some point a country won't try to aquire nukes to attack another country (however unlikely that is). Even if the risk is technically small, it's too great to make the idea of every country having nukes anything more than a nightmarish possibility (o/c even one country having nukes is a nightmarish reality, but that's not the point either).
Then there's the Somalia problem...