Yes. Madsen from O&S Cattle wore one this past weekend at the McQuade and Brian Autry used to wear one.
I don't think they should be mandatory but there are probably more seriously injured runners and infielders than their are pitchers.
Personally I've always naturally put my arm up when running to first if I know the ball is coming. Put my arm in a 'V' shape to cover my temple and jaw. Whenever I know the throw is coming.