I think everyone should have a current passport.

A passport is a very valuable document and I would not EDC mine. Someone up to no good could create a mess for you if they stole it or found it and then used it for all kinds of identity theft uses, including getting arrested and passing himself off as YOU. Unless you lived near a border and could foresee a reason for needing to cross over at a moments notice, like maybe living/working near Seattle after a massive earthquake and you have friends/family in Canada, the likelihood of identity theft and the hassles associated would outweigh any situations I can think of that requires instant access to my passport.

Actually, in past massive earthquakes in the Pacific Northwest, I wonder what the border control situation was like? Would Canadian authorities be reluctant to let Americans cross over after, say, Seattle is devastated, fearing an influx of American refugees/evacuees who then might become a burden on the Canadian gov't, or vice versa?