I can't imagine that any bicycle tourist would use hydraulic disc brakes. This entire discussion centers around cable-actuated brakes like the Avid BB5 and BB7. In any event, removing a hydraulic brake caliper isn't as difficult as you make it sound. If the brake or hub is really screwed up, you can remove the caliper alone, allow the brake fluid to drain, then leave the hose and levers in place. Obviously, the downside is that you need to refill and bleed the system once you get around to repairing it (presumably at a bike shop). Removing the caliper, hose, and lever as a unit is still relatively easy: two bolts for the caliper, 1-2 screws for the lever, and a few hose clamps or zip-ties in between. I couldn't imagine it taking more than 5-10 minutes...

Regarding tools: many multi-tools now include the Torx bit required to remove a brake rotor. It's difficult to imagine that someone who rode a bike with disc brakes wouldn't own one... especially if they're planning an extended tour. Anyone who tours and can't adhere to the 7 Ps probably deserves what they get, unfortunately.

I can, too! Luckily, in my experience, it doesn't happen nearly as often as you might think. I've been using my sub-standard mountain biking skills for the last 3 years trying to destroy a set of disc brakes. I have managed to bend front rotors a couple of times, but field repair (read: bending them back) was possible, and relatively easy in each case. Damage occurred on terrain that I would never consider traversing with a touring load, BTW.