From my point of view it seems like everybody else (yeah I know it's not really that way) does it, so why don't I do it too... just to follow the crowd on at least one thing :)

This is my SecondLife avatar, "headshot" as you can see... I added the background and flag (And no, that's not my SL name, my SL name is ironically enough, Lupine Woonona... Yes, "Ursine" uses Lupine as a name >.> )