Barefoot sandals

So, this must be a fad.  I just don't get it.  The entire point of  wearing sandals is to protect the bottom of your foot while not confining your foot to a hot closed shoe.  If you don't want to protect the bottom of your feet, why not just go barefoot?  Why bother with some bit of whatnot you have to tie to the top of your foot?  Can someone please explain?