When and why did governments impose restrictions on money creation
In any healthy economy, the central bank is independent of the executive government. (Since the central bank can be thought of as part of the 'government', I want to be specific about which parts of government I am referring to&mdash;by "executive" I mean the body of people who are in power and who administer policies.) 

This separation is in order to separate fiscal policy from monetary policy, as this makes it easier to achieve monetary policy objectives. Otherwise, the executive could enforce money creation merely to achieve some objective, such as increased government spending or a decrease of local-currency denominated debt, but this would send inflation skyrocketing. Instead, the executive (through the Treasury) sells bonds on the open market. Any entity is free to buy those Treasury bonds, and the price is determined by the market. (An executive that controls the central bank and forces them to buy Treasury bonds is not really independent of the central bank&mdash;it is just a show.) So, the Treasury selling bonds is how the executive raises money for itself, but it also increases the demand for money, so the central bank needs to be part of the group of entities that buy the bonds, in order for interest rates to remain unchanged. Needless to say, when the central bank buys bonds, it is increasing the supply of money.