I for one think there are changes that affect high school sports, that are affecting numbers across the board, not just in softball. Pay-to-play is one. For a teen-ager that might have a high interest in the "being part of the team", paying for that privilege tarnishes that feeling a little bit. Players have so many more choices today, not just among school sports, but also other activities. The associated part of that is every activity wants its participants to be dedicated to that program, whether it be a sport, the school play, etc. There should be room in a school for the kid that has more then one talent, and it should not be perceived as a lack of dedication.
The role of parents is another. Not all parents subscribe to the theory, and certainly don't teach their kids, that if you aren't playing, you need to work harder and get better, it can only be politics, or the stupidity of coaches. Instead of learning how to handle adversity and the benefit of improving your skills for something you want, they simply drop out. The role of society in general is also a factor. By the time your child has reached the high school level, you have probably witnessed literally thousands of sporting events. Many parents and students, don't then choose to support any sports that do not involve their child/them. At one time, going to watch a high school football/basketball game was as much a social event as a sporting event regardless of the teams record. In my community, it is less every year. My point with that is that it becomes less of an honor/status symbol just to be part of the team then it used to be.
One fools opinion