The reason that printing currency is a delegated power is because, our Nation needs to be able to trade among itself. If two states had different types of currency from one another it would make trade and travel between the states much more difficult as money from FL and NY would likely be different and likewise useless in each of the other states.
They began to get greedy and wanted to make a profit with the money that people entrusted to them.
The Agricultural Revolution of the 18th century paved the way for the Industrial Revolution in Britain. New farming techniques and improved livestock breeding led to amplified food production. This allowed a spike in population and increased health. The new farming techniques also led to an enclosure movement-wikipedia