This isn't necessarily related to the articles, but it is related to barefoot training:
I love to do my "plyometric" training outside, on grass, barefoot. I get funny looks and greens stains on my feet and socks (when I put them back on), but hey, who's counting.
I like (1) the proprioception practice I get from uneven ground and the texture of the grass (even the temperature of the grass/soil), (2) the training stress applied to the foot/ankle/toes that is largely absent in shod locomotion, (3) the "low-impact" nature of ground when the soil is damp, and (4) the way it helps me reconnect with my inner "little kid" (useful for a father of a young son).
Even a "flat" football field hides a lot of variation -- especially if you are barefoot.