There are 2 big problems with using carbon for touring bikes.

1 - limited sizes, not a problem for most, but if you want something unique, metal (normally Steel or Titanium) is far easier to be worked for a on-off design

2 - the biggest problem, lack of mounts (braze-on's fender & rack), there arn't many carbon bikes out there which have these, don't see it as an issue for manufacturing, and I'm sure they would be as strong as any other frame if fitted, but no-one spec's them with these (plenty of carbon bikes have disc mounts, so if this can be done a rack mount shouldn't be too hard.

I think that unless there is a large increase in the number sold, there won't be the demand for touring frames to be made from CF.

For changes to makes bikes, lighter, an internal geared drive train with Gates Carbon Drive would be better than a carbon frame