Using a different frame material for a tour isn't in any way the same as Columbus discovering America, but I get the point you are making.
The issues of using carbon fiber in a touring bike seems to me would be just a few. One, there aren't really any carbon frames devoted to touring, that I know at least. So your load and where you carry it is a little thrown together to fit the bike instead of the bike fitting the load. It seems that an ultralight approach to touring should be used and racks that attach to the frame or fork would be best avoided. Two, any kind of repair that requires tightening a fastener on a carbon fiber piece requires a torque wrench, which is just another tool to carry.
Aluminum has worked fine for touring bikes; my Novara Safari is an aluminum frame and has worked fine. I prefer steel, but would take an aluminum bike too.
There are racks that will work better with carbon bikes, namely the axle mount racks from Old Man Mountain or from Axiom or Tubus (Tubus Fly) will work as the weight of the panniers are borne on the wheel axles, not the fork or the stays or rear brake bridge in the case of the Axiom Streamliner DLX (I own this) or the Tubus Fly. I also have an Old Man Mountain Sherpa rack and this is one tough rack and works with CF frames. In fact, OMM has customers who use these racks with their own CF bikes on tours no problems whatsoever.
The concern I have is really not about weight if the proper racks are used, but rather the weight placed that may effect handling. Over 30lbs of well distributed load up front and back on a bike, the bike becomes a little bit twitchy as most CF bikes does not have the necessary wheel base and relaxed steering angles to give a more benign and slower response of that of a touring bike. But around 25 to 30lbs is all I need for a light setup and the bike feels stiff, confident and responsive still. This is unlike a conventional tourer that it ALWAYS FEEL sluggish, because if it's a tank it sure will ride like one.
I've toured with both aluminum and steel bikes and I find both to be just fine. I suppose the negative press aluminum frame gets is due to the harsher ride that people think they are getting from aluminum and less with steel. But I think this is due more to better fitting, tires used and inflation of the tires rather than the material itself. But bike companies move in packs and sell in packs. When steel is good, everything is now sold with steel in mind in the touring world. Not too long ago though, the opposite was true with aluminum is lighter and steel is heavy.