"I'll add my speculation that folks who don't find the straps beneficial are probably not getting much benefit out of their poles. My straps take a LOT of weight, especially going downhill. That's weight my knees, ankles, and feet don't have to bear 25,000 times per day. Even if I were Popeye, my grip couldn't maintain the loading my straps take."
In at least one case, namely me, you'd be wrong. I don't use straps, preferring to cup the butt of the handle going both up and down, and I am definitely not Popeye. And I most definitely get a lot of benefit from my poles. If you look at the anatomy of the wrist, specifically how it is designed to flex, gripping the handle or even using a strap causes the wrist to flex side to side instead of up and down, the natural direction. By cupping the butt of the handle, one has a universal joint that allows moving the pole in almost any direction with a high degree of precision using only slight pressure from either the thumb or ring finger. I can go all day this way with no forearm fatigue at all, nor the wrist rash/abrasion associated with a broad strap. As for going uphill, the mechanical advantage is similar to a spear throwing stick as the triceps and lats engage. It does require a modicum of fitness, but nothing unattainable if you work out at all, although it may not be for those with tender hands. I do use a 2 mil Perlon retaining wrist loop/cord attached to the pole just below the handle to avoid losing control of the pole for all the possible reasons that can happen.
"Some people seem to use their poles mostly as feelers; I can understand why they would find little benefit in the straps."
Cupping is very well suited for this ability, and I consider it to be almost like having antennae in probing ahead to determine terrain texture, presence of snakes in thick brush or under overhangs, among other things, especially at dusk, dawn, and night.
Not trying to start an argument here, but merely to give my perspective on a technique that has only been mentioned in passing so far. As always, HYOH.
Edited for content.