Exactly "Otoshidama" is a lot of money for children, but it is strange that children don't buy anything.
Savings are important for adults. I think that children should use money, because the economy is activated by the personal consumption.
It is said that "Money comes and goes". A waste is bad, but if many people want to save money for their old ages, Japanese economy will become inactive.
Saving money is important, but the usage of money is also important for Japanese economy.