I think most of us have fairly similar nutritional requirements given that we are all derived from the "bottleneck population" when humanity was reduced to very small numbers. What else is there besides protein, fat and sugar plus a handfull of vitamins and minerals? Most hiking is done at low levels of physical output for long periods. Being omniverous we can fuel a hike on just about anything, from raw steak to M and M's.
Energy packets are perhaps the most expensive and over-hyped form of sugar known to man and they pack a heavy environmental (packaging) impact per calorie to boot. I buy table sugar in 5 pound recyclable bags and add it to home-made protein drink to which I can add anything else I want. I drink one on the way to the hike and another along the way (in all 4 seasons). Peer-reviewed scientific articles show sucrose to be suitable for pre-event loading, fueling during and recovering from elite level aerobic endurance sports.
The fitter you are the more you use fat for fuel anyway but of course fats always burn in a carbohydrate flame so some sugar is always required.
Possibly, carbohydrate delivery devices such as Gu are a symptom of our overly-superlative culture. Superlative as in being the "best you can be", "shattering" records, "pushing" one's limits, "killing" a mountain, "crushing" a trail and so on. Most people probably just like to go for a relaxing hike and wish to enjoy a nice lunch somewhere.