There are hundreds of reasons why people won't use a face pic as a display if put in a public pic, I've got a few reason myself.
However it's always nice to see a little smiling face isn't it.
Comment in, and send a face pic to anyone who takes your fancy
Mostly I don't have one to stop putting people off. Sent two in the last two days and neither replies after
Maybe they fainted as I was too sexy, my story and I am sticking to it.