Because I've had this conversation too many times before:
If you use the urinal, wash your hands. Even if you didn't have to touch it to flush, wash your hands. Your dick is not "cleaner than the door handle", wash your hands.
Was sitting in a stall and heard a guy leave the urinal and loudly bitch to nobody in particular that he didn't touch his dick while pissing so he wasn't going to wash his hands, because, "fuck that shit." Why are people like this?
Ever see the Mythbusters episode where they lined up toothbrushes to see how far fecal matter traveled. Right near the toilet was the worst but nowhere was safe.
So yes washing hands helps but it's not the be all, end all solution.
I'm sure someone will disagree with me but I think protecting ourselves completely from infection isn't a good idea. Particularly after reading Immune (good but not the best resource) I think washing our hands all the time or using antibacterial soap is not a good choice for our individual health and immune system strength.