Why should the bank give you free money? Nothing is free so you will have to loan it. Banks loan out their money because you will have to pay more money then what you lend from the bank.
For example, if im a government and i want to build a railroad, why i need a loan from central bank? I can print my own money without loan, without interest and build the railroad.
It's easy to say that. But you need to consider that when you print more money the value of that money would decrease due to inflation. C'mon it's just a simple economics it's called "supply and demand". Most bitcoin users know that.