Keeping your hard-earned wealth is hard. The state wants most of it in taxes. A couple of weeks ago I explained how socialists use randomness to steal your wealth. Now economists want to use a cashless society to take it.
The real issues involve the ability to use monetary policy to (1) stabilize the economy, (2) issue credit in response to financial crises (act as lender of last resort), and (3) be able to inflate the price level in an emergency where it is necessary to engage in partial default (in real terms) on government debt. To achieve these ends effectively, it is extremely helpful for the government to control the unit of account and the currency to which most private contracts are indexed.