Ever get hit with a rock or shot at while on a motorcycle? Or have someone stopped in traffic open their door on you while you're flying along splitting lanes? Or even run over a large pothole? Think about it. A motorcycle offers no protection at all from people (possibly rioters), animals, and from the environment. I would take one with me if I could (say strapped to the back of my truck/suv), but I would want to start out with a more substantial vehicle and see how far it gets me. At least then I'm starting out carrying more gear and I'm much better protected. It's easy to get rid of something you don't need, but not necessarily easy to get something back (or find something) you do need.

The other thing too is, in my SUV/Truck I can travel nearly 1,000 highway miles before I need to put any fuel back in the tank. Most dual-purpose motorcycles only get half that, with little room to carry more fuel. Even the militaries diesel bikes (designed for overall fuel mileage) get 600 miles at the most. I wouldn't want to ride one for 600 miles though, my back and legs would become useless.