Because not living in a completly sterile enviroment will kill you?
This is what humans are becoming, scared of bacteria and a bit of invisibly small poo (that gets released in the air we breathe anyway everytime a cow or a human or a cat or a dog farts)
---------- Post added 2013-01-03 at 12:29 PM ----------
Or even better! no seat no lid no toilet! lets all go outside to poop in a hole, you don't have to touch anything, you only need to have a good balance.