I think it should be each individual's decision to wear a face mask or not while at the plate. Similar to each person's choice to wear a mouth guard or not. If you want to take the risk, it should be your prerogative.

I think they should be mandatory. I remember not liking the idea growing up of having to switch to and get used to wearing face masks that my coach mandated--but it didn't take long for me to appreciate that rule. For the amount of games we played it wasn't rare to see a face injury... or many times an injury that would have been if not for the mask a girl was wearing.

I remember one large weekend tournament an ambulance came to the complex on three occassions--all of which were related to girls getting hit in the face by the ball. It just doesn't seem worth the risk, especially because, in my opinion, it doesn't take long to get used to wearing a face mask while up to bat.

Here is an article about the third Arizona softball player to have a serious face injury:  3rd player with facial injury eyes using mask

I think under a certain age you can consider making it mandatory, but after high school it should be up to the player since in high school pitchers should be accurate enough not hit people on a regular basis and hitters should be experienced enough to react to a wild pitch.

I think it should be the player's choice. Part of playing the game is the idea that you might get hurt. It helps separate good players from great players. It is also quite distracting to look through bars as you are trying to track the ball.

I believe face masks should be mandatory for a number of reasons.  1) This requirement relieves the school/league from any liability, 2) It is not that difficult for batters to obtain face masks, 3) It doesn't obstruct the batters view when batting and 4) It easily prevents the sometimes fatal head/face injuries.