Hell, forget about The Big One...disaster preparedness is always a good thing. Especially around here, where a single ice storm or snowfall is enough to shut areas down for weeks at a time. That's why my parent's place in NC has a 7kW generator, running off of a 500gal LP tank...enough power, hot water, and heat for three weeks. Plus enough snacks and water to last that long. The logic being, if you're completely isolated for longer than a month, things have really gone to hell and you won't be waiting for the grid to switch back.
That's part of why I installed the radio gear in the van - knowing if something happens or I get stuck somewhere and basically being able to communicate on almost any emergency frequency out there is a good thing. Cell phones (even for minor, local emergencies) take a shit when things go south - the only traffic in and out of an area often times is handled by radio.
Survivalism just isn't for the end of the modern world - it has its practical uses.