My reason for including the bike in total weight is just to be consistant with the backpacking crowd. They include everything except food, water and what they wear, and as the bike is the single heaviest thing in a tourist's kit it seems strange not to consider it. Or should we think of the bike as the backpacker's boots and that we "wear the bike"?
Like I said earlier, this is not the case. Just a quick browse on backpackinglight.com led me to
this list. Check out the "clothing worn" section.
And I'm not sure what MassiveD is on about. I work in a bike shop and know plenty of hefty customers rolling around on 16 pounds bikes. There's no reason a 300 pound rider can't tour on a 16 pound carbon bike if they so choose. And there will be a pretty big difference between a light bike and a heavy bike.
Think about it this way: You and your buddy go to tour the mountains. You get identical 10 pound base weights for some insane reason, and, just for fun, you both weigh about 180. You roll out on your "fast" bike, let's say 20 pounds or so, and he decides to take his "touring" bike which is pushing 35 with racks and fenders. If you keep the same pace, one of you is doing a lot more work. One of you is traveling light and the other is traveling ultralight. In percentage alone, the weight you must move from point A to point B (the definition of work) is a larger percentage from bike to bike once you get into UL territory.
Again, I'm not here to vote on where the line is drawn, but I think it's only fair to factor the bike into the equation.