This quote presents us with a major problem when developing children's products. This is because they are usually made by "big people" who are sure they know what is good for children. What's more, these things are usually bought by "big or even very big people" who know exactly what children need.
The best example of this is school bags. These are usually given to children by their grandparents when they start school. The decision is usually based on the price. The fact that there are often some models that have an impractical carrying system, for example, doesn't matter at all.
This is because we no longer remember what we wanted as a child. That's quite a claim that I'm making because, as a paediatric surgeon, it must be very easy for me to remember. But when we create something for children, we should remember what we would have wished for as children - for example, a good shoe.