I almost never carry sharpening gear with me into the wild. For the most part all of my knives are sharp and will retain their edges plenty long. And I generally have more than one knife. For me sharpening is a job best done in my shop at home. While you can spin a scenario where having the ability to sharpen might help you in the field I don't think it's mission-critical for most of us.
Really? I touch up edges all the time in the field. Knives, axes, hatchets, ect. Even if they don't get completely dull, I find it's best to maintain the edge as best as I can while in use. A sharp knife cuts with less effort (and less energy expenditure) and is safer than one that isn't as sharp.
Even in daily use I find myself touching up blades often. Cut up some cardboard boxes and an edge can go from hair splitting sharp to butter knife dull real fast. Even a quick stropping can restore a lot of that lost edge.