I don't get the big deal about kids riding on the sidewalk. I mean, it IS safer than riding in the street when you're a kid on a little fixie with coaster brakes. And as those kids grow into teens and if they are interested in cycling to any degree they will automatically WANT to ride on the roads. How the heck can you get anywhere riding on the sidewalks? (Actually, come to think of it, in my area there are many places without any sidewalk so you have no choice. But in any case . . ) The road is 100 times more convenient.
But as for helmets, it makes me mad when I see grown-ups riding with their kids, but only the KIDS are wearing helmets! What kind of message does that send the kids? Plus, I think riding on the road without a helmet is way too dangerous.