The value of money is something which children should be taught from the earliest possible age. In the modern day environment, kids seem to get given what they ask for, rather than be shown the hard work it takes to be able to provide it for them.
Pocket money is a good starting point, and by giving them a small amount each week and letting them decide what they spend it on helps to teach them about independence, and how the choices they make can make a difference down the line. For example, if a child is given 2 every Saturday, and spends it all in one go on sweets, and then on the Wednesday sees a toy they want for 1, they will quickly realize their haste the previous Saturday. They will only learn if they are made to wait until their next pocket money day so they can afford the toy simply giving them the extra 1 (not much money to an earning adult) in advance will not teach them the error of their ways.
Furthermore, children can be taught the importance of saving small amounts of the money they get so later on down the line they can either shell out for something a little more extravagant than normal, or cover an emergency cost they didnt realize they would...