Despite dire warnings about how bad it is for you to go outdoors barefoot or -- horrors! -- run barefoot, I've found it to be a lot gentler than doing those things with shoes on. Partly it's because shoes let you get away with all kinds of sub-optimal walking/running technique -- heel strike first and foremost among the villains. Barefooting does not allow you to get away with slamming your heel down first; you hit you bare heel once on the pavement and you'll immediately switch to forefoot landing, which is far softer.
Shoes also try -- with only limited success -- to replicate the wondrous range of capabilities already present in the 33 muscles and 26 bones of a normal human foot. The result is atrophy of those very capabilities we were born with. It's sort of like the call into tech support about the malfunctioning computer mouse: "It's hard to press the buttons through the plastic dust protector" ... "If you remove it from its packaging it will work much better, trust me."
Also, your feet are lighter without shoes. And you save mucho dinero $$$ when you aren't buying expensive running shoes every few months (feet don't wear out like shoes do; they actually get stronger).
If you want more info about the beneficial biomechanics of bare feet (including an animation I did to illustrate the forefoot landing), check out the page entitled, "Natural Locomotion".
Another benefit of bare feet is fresh air. Athlete's foot fungus thrives as a result of cooping up feet in the warm, steamy interior of shoes for most of the day, every day.