Walking barefoot, over all manner of surfaces, feels good, increases your connection to your surroundings, and slows you down.
I've done it lots, both in the countryside and in the city. You have to watch out for spiky plants and fox shit in the country, and in the city you soon learn which surface textures require more care :-)
"Where would I find enough leather to cover the entire surface of the earth? But with leather soles beneath my feet, it's as if the whole world has been covered." - Shantideva, 8th century Buddhist monk