I smile when I see people in weird places without shoes too :) Feeling cold cement and tile floor on your feet is not the same as feeling the Earth, but at least it's more freeing!
I remember when those goofy five finger shoes came out and I was seeing people running in them all over. I didn't get it then...but now I totally do. It's a way to get minimal support and protection without the huge rubber sole that most sneakers have these days. :)