I agree that team sports definitely provide some education, or life skills, that transfer to many different parts of a person's life. I believe it provides the critical skills of learning to work with different types of people, learning what it takes to succeed, experiencing & overcoming failure, how to compete, and developing leadership skills, to name a few. My children will be involved in team sports as long as they are able to compete, be successful, and they still enjoy doing it.
Regarding the topic of roster sizes, it is probably not a one size fits every program. Each coach/administration determines what is best for them to meet the goals of the program. I think there is a point where a roster can be too small to have a continually successful program, probably around the 32 number. Ideally, it is probably 35-45. I also think that if the goal is to have everyone practice/develop as a team together, there starts to be diminishing returns beginning around the 40-45 player mark. Just my personal opinion.