Intimacy and cards
Why are we interested in things like Tinderbox cards? Douglas Johnston rejects the usual suspects. It's not portability: a treo is more portable than a bunch of 3x5 cards. It's not fear of technology: I like tech, and so do you. It's not cost.
Johnston's candidate is intimacy. He starts out at the Bolter test (reading in the bathtub), which is a misstep, but then he gets it right:
Pick up a nice little leather-bound journal, grab a smoothly-writing pen, and all of a sudden, things become sensual.
I'd suggest that other factors are transparency, immediacy, and reliability. Most of the time, a solid XML tool like Tinderbox delivers these just fine, but when you're on the run in Rome or you're stuck in Sheboygan, the physicality of ink and paper is reassuring -- and, when you're stuck or on the run, this kind of primal, direct assurance is what you need.