Is there a reason why they don't make this for adults? Because I can't think of a single one.
There has been quite a few discussions by people on the internets who want their kids to ride with them, and people who believe it is too dangerous.
While I LOVE riding my scooter and would LOVE to bring my little fat dog, Spike along. It is just too hazardous. However, in the case of a Zombie Apocalypse, that would change.
I don't have kids, so the point is moot. I believe it is up to the parents to decide. But if I have to say, they make some of COOLEST gear for kids who ride.
Kids helmets (and I suggest full face), offer a great selection and you can add a bit of personal flair by adding these great pig tails by Hansen Enterprises.
How about some helmet ears from Aerostitch.com. You gotta admit these are uber cute!
There are also plenty of fully armored riding suits for kids, leather and kevlar armor from The Iron Horseman.
Since none of us adults will ever look "cute" ever again, the best we can do might be this SpongeBob SquarePants Pavillon helmet made with a carbon fibre shell and lined with nappa lambskin. Alas, only 200 units of this Ruby Pavillon would be available and that even only in Europe and US. Oh, don't forget the price...around $1,200.00, at LEAST! You gotta pay BUCKs to dress like a KID when you are an adult.