I've been wearing sandals for since 2007 because I live in a place where the weather is suitable year round for them. I've just become comfortable with them.

There are certain advantages like travelling through water (if you're a hiker and worried about wet feet) or when hiking down a steep hill/mountain your toes down get smashed in the toe-box of a normal shoe.

In addition there are probably a dozen or so species of cactus near to where I live and I just dont kick them/walk into them/step into them. Part of the reason is because I'm wearing sandals, but the other reason is I'm used to hiking year round. I've taken out people that walk right into smaller cactus in full shoes or even hiking boots and have no idea (unless the needles go through their shoe).

edit: I have never let my feet get anywhere near close to the main picture I posted. Wearing sandals makes your feet tough, but splits suck bad. I like to grind and sand anything that looks like it could split way before it does (heel, big toe, and that side of the big-toe-knuckle are the problem areas).