That would change only nominal valuation, not real values. Nobody becomes richer or poorer when nominal value of currency changes. btw. Central banks interest

That would change only nominal valuation, not real values. Nobody becomes richer or poorer when nominal value of currency changes. btw. Central banks interest rate can go negative only little until it becomes cheaper to hold money assets or transfer them to other assets. Nobody holds cash if interest rate is -5%. This is why deflationary spiral can't be countered with just going below zero.