This makes more sense economically. Physical products in general degrade in value over time. Cash by itself does not degrade in value over time. Using cash to represent products is a sort of mismatch. If the products' value degrades so should the value of the instrument representing said product. I don't know why they use negative savings interest rates when the government can provide the same service through QE or l…
QE causes asset bubbles. Negative interest rates promote (in theory) consumption over saving. Economically, these are uncharted waters.
Inflation and deflation are side effects arising from this inaccurate representation. I will hold on to a dollar differently then I'd hold onto a physical product. Inaccurate representation therefore leads to unnatural behavior. Often the product a dollar represents can degrade to worthlessness while the dollar maintains value.
By making the dollar degrade explicitly , it forces people to treat a dollar as one would treat the majority of physical products in the real world: as an object that degrades with time.
Think about it. If my assets are represented by physical products with real value, what is inflation and deflation? The concepts becomes non-existent.