An ultralite approach to touring makes perfect sense, but putting something on your back does not to me. I assume we are talking the ordinary touring world. Not some kind of specialized super hero role where the pack has to be there. I think this is where we loose track. Consider two thought experiments.

1) Imagine this thread is about clothing. Can we imagine a great round of applause for the new item of clothing under consideration that adds 5 pounds to your back and makes it impossible for your back to breath? Round of applause, who wants to pre-order?

2) Imagine we are talking about normal loaded touring, 4 packs two racks. Now I come up with an idea where you have the same basic capabilities but you don't have to carry anything in the bags, your total load is just the bags. Sound like a sufficient step forward? With my gear that would be about what you would have if you had 5 pounds of stores in one rack and pack. So prior to this a lot of people would have been willing to carry the 4 pack, and 40-60 pounds of gear. But we have now saved the 40-60 pounds, but it still isn't enough. I gotta cut out that extra five pounds, even if it means I have to wear the piece of clothing in 1) above. Doesn't make any sense to me. I think the ergonomics speak to being able to carry the extra weight but in a better way.