The first point about acting more aggressively than you would otherwise isn't just hypothetical. In the mid-1980s, Richard Perle, one of the prominent members of Rumsfeld's circle, originally opposed SDI because he thought that the technology was too unreliable and too expensive to be worth it -- better to build more offensive systems.

He later changed his mind, and in an interview said that he thought the key benefit of an ABM system wasn't necessarily whether it would stop missiles or not, but that the mere existence of a system might give a presdident the confidence to act boldy in a crisis, rather than backing down for fear of an American city being nuked. It was quite clear in Perle's discussion that he hadn't changed his mind about technical merits, but that he wanted presidents to act as if we had an effective missile defense, even though Perle doubted it would actually work. In other words, Perle is willing to lose Seattle in order to have a bold foreign policy, and he wanted the president to also be willing to lose Seattle -- even if the president thought he *wasn't* risking American cities.

The other "neoconservatives" haven't been so blunt, but if you look at the writings of Rumsfeld, Cheney, Wolfowitz, etc in the 1990s, it is clear that notion of enhancing the president's willingness to take on a nuclear-armed opponent is a key driver. What really underlies their thinking isn't protection against N. Korea lobbying a nuke at us for some crazy reason some day, but, so that we are willing to enter wars against nuclear-armed nations (principally China in their 1990s thinking).