Check out this article
I think these hand-cranked LED toys are social design, not just because of the "green" aspect which is intentional, but in that they can shift our views of where energy comes from.
Toys that run magically on batteries run down... and we just go buy more. The child thinks that energy is something you go and buy - a commodity that never runs out. This toy might show children that energy is a resource that requires effort - it's not magically stored in a coppertop. Energy is work.
We look at the world as a resource we can exploit - and we need to remember that to get something out of this world you have to but effort in - no free rides!