Some say that younger audiences wont use forums.
Forums are old. Outdated. They don't look great.
Just look at communities like WarriorCats; a community for 8 to 14 year olds. It has 17.6m posts from 64,396 members.
If you can find another platform that racks up these figures, then be sure to use it. Until you can, I'd look at forums as still the best, most cost-effective, and most popular platforms for developing successful communities for all audiences.
If you're not using the best platform for developing a community, you should have a good reason.