I think you've outlined it well--if you're concerned about organics, carbon makes good sense. To be effective, it needs an adequate amount of contact time, which implies matching the flow with the correct amount of carbon. I don't know which filter makers might test their products for those parameters.
For folks who travel in alpine areas (e.g., western US mountains), organic contamination is usually of no concern, and carbon would add no health benefit. It can improve the taste of stagnant or slow-moving water, though.
You have to be careful about drying carbon between uses, since wet it can become a great home for bacteria and mold.