I'm a litte late to the game but the Boston Globe wrote an article about the possibility of pitchers wearing a helmet in the future.
You can read the very short article here:
Yeah, it looks a bit stupid in the photo, but really, for the Marlins it is probably not. Since the Fish wear black hats, all you have to do is put the Marlins emblem on the front of it and it would be pretty unnoticeable.
The Marlins haven't had much of a problem with pitchers getting in the head with line drives. But that doesn't mean it can't happen. The team has a lot of money invested in some of the pitchers, so it might be a decent idea, should this ever come to pass.
Of course, a little depends on the weight of the helmet and how it feels to those who are throwing the ball. Probably the best way to institute it is making minor league, college and high schoolers get use to it first.
I'm am not one who thinks the players should wear armor because of just one person. Much like I don't think I should have to take off my shoes to board every flight just because some fool tried to blowup his foot on an inbound from Paris.
But I'm reminded of Babe Ruth's greatest fear in the game, which was, and I paraphrase, that he would kill a pitcher with a batted ball.
Pitchers finish their delivery awfully close to the batter.
I have heard of worse ideas.