I would think there is a concern about what might be considered attractive to children, not really designed to put off adults with a developed sense of aesthetic, who are already users.

Agreed. These designs are serving their purpose, to deter children.

The general theme in these comments is that these designs look too modern or up-class. The reason it looks like this is because its a product for adults, children generally don't appreciate this kind of design so I would imagine this works pretty well.