One of the stated goals of Communism is the end to greed. By the top down control of the economy the communist will see to it that resources are fairly distributed ending greed by, in essence, ending wealth.
What they fail to realize (or perhaps they do) is that Communism doesn't end greed. It only changes it from a greed of money to a greed of power.
It has been proven time and again that a poor child can rise up into wealth, but a powerless child will always be powerless.