My daughter pitches and I have the same concerns, but have also been told by many that played or coached at the college level that coaches in college don't like to see the mask. Since she hasn't worn one since 14u, college coaches have not seen it on her and we have not had any feedback from the coaches currently recruiting her.
One thing that would help the pitchers a lot at the 16u, 18u travel ball and high school level is for the umpires to recognize the pitches on the corners of the plate as strikes. Many of these umpires force the girls over the center of the plate to get a strike call. First, these girls work hard to learn to throw their pitches on the corners and should be rewarded for the effort. Second, forcing the pitchers over the middle of the plate results in more balls hit back up the middle. We have actually had umpires widen the strike zone after a line drive hit back at the pitcher. The smart ones know how it works.
Personally I think college will have to pave the way. That is where a lot of these girls have their sights set and if they don't see the college kids using masks then they won't. I'm not sure any one other than 3rd and pitcher should need one. You can make a case for 1st, but how often is 1st that close.