Here are some possible explanations:
4. Logistics - many churches have a youth group where kids go instead of services. Having never attended a full normal service (or only for Easter or other special occasions) and not being used to it, they don't want to sit through a full service and get bored by it.
That's a good point but I think it could be expanded. Specific religious programming for youth, college students, young professionals, etc really came en vogue during the previous religious awakening that coincided with the rise of "Me" culture (1965-1985). It might have atomized the Church to such an extent that inter-generational, Church-wide fellowship and study has been neglected - making it difficult for individuals to be challenged to grow within their faith and transition to new stages of life within the church.
