Teens are cynical. Once a kid has aged past Caleb and Sophia (which is probably younger then the wts thinks) the wts has nothing to offer them.
Older kids are pretty media savvy these days and I agree with other posters that teens and preteens know when they are being fed propaganda.
I really wouldn't be surprised to see the wts institute some sort of after meeting or before meeting Sunday school. It may only be 25-30 minutes but it would a video, short discussion and a fun craft. They know they need to get young kids to want to go to the kingdom hall. The kid begging to go gets the parents motivated and attending.
They are working hard to improve their youth retention rate.