I agree - I believe some sides have to be more about marketing themselves to a younger audience - attend the festivals (and dnace at) the big folk things that attract the youngsters - Sidmouth, Towersey, Sweeps etc).
I have been dancing since I was 3, i'm now 25 and I can honestly say that while some sides are struggling, others are making real headway and encouraging younger members both into the side, and then latterly to stay in the side they have joined...
Dare I say it - I think the quality of the older members dancing is a pull factor, looking like they enjoy themselves and being really welcoming of younger people is key.
Also - Morris Kit is a MAJOR factor. Having danced with Gundulfs aged three -eight I can categorically say that wearing the kit is 'nice and cute' when your that old and then again when you're a bit older (say at an age when you're not so bothered if the people from your school see you with a flower head band and wearing green and yellow tunics)then the kit is fine. But is you're 17, you want to be wearing the cool kit of other sides...
This is the same for other sides i've danced with too - dare I mention Oast Ouse Oppers kit? or Offcumduns kit? Not exactly comfortable and make you look like a sack of spuds.
I think that Image is important - as is the friendliness of a side - to young people. And i would know. As i am young. he he