Here in the White Mountains of NH, hiking is very popular on the thousands of miles of maintained trails. One problem with the poles is that they are causing massive erosion of the trails.

As you hike a popular trail, look closely at the ground - you will see a myriad of holes that have been poked into the soil by the tips of the poles. Soil is loosened, churned up. The next rain washes the soil away. The next day more hikers and more poles. Later on more rain. Cycle after cycle.

The result has been that for many miles the trails have become pathways of exposed tree roots and rocks, and the trails are often even a foot or several feet below grade. You are walking in a trough.

As a youth in the 1970's hiking poles were uncommon. Sometimes hikers might use a stick, but that has a different effect on the ground. For some reason since then the hiking poles have become commonplace (I think it is partially the "cool factor" of looking the part of "hiker", the erosion problem is enormous, and I have taken to bushwhacking off-trail instead of using what I feel is a damaged trail system.