I've never seen as many "kid oriented" schools as folks say. In about 5 years of TKD now. I know they're out thefe, and I'll see them on occassion, but everyone Ive sparred at tournament is 16-35. I started at 16 and was the only person under 22 In my age group for 3 years.
In my experience, the folks seeing it as a "kids martial art" either haven't trained or hadomitted exposure i.e. one school.