Banks don't create money out of the air. They don't. There is a demon called inflation. As soon as the banks continue to print more money, that demon will begin to devour them and the price of the currency will decrease until it becomes more expensive than the paper on which it is printed.
Central banks try to maintain some measure of balance, and it is the poor that pay the price, not the rich.
Here the problem lies not in printing money.
Printing money is a symptom of a disease.
'Printing money' is misleading. Most money never exists in physical form, it only exists in the form of loans from commercial banks, where money is created as a number on a computer. There is some regulations on how much money can be created by banks - they have to hold some capital in case people default on their loans - but central banks create only a tiny proportion of money in the modern economy.
The 2008 financial crisis has clearly shown that banks do not hold enough capital to back up the money they create when there is economic hardship. Hence why Satoshi included in the genesis block an article from the Times: 'Chancellor on brink of second bailout for banks'.