So what about if the government decides to devalue the currency by printing more money? Hasn't that 'quantitive easing' eroded your stored value? Your balance might be the same but the purchasing power and thus value isn't. Best bit is you won't know till after its done, way after.

It might be a nice incentive for investing money to keep value ahead of inflation but to the man-on-the-street its a bit like robbery in some sense in that it deprives you of the full expected value of your funds.