[sp332]

Inflation in the US has been pretty low lately, which does not really encourage investment (relative to hoarding). That's at least partially because huge banks control the interest rates. If someone other than huge banks could control the rate, they could make investment more enticing compared to hoarding.

[highfreq]

The primary lever the Fed has to influence inflation is interest rates. Low interest rates tend to increase actual investment, in factories new businesses, etc, and eventually drive inflation up. Increasing interest rates now would most likely trigger a deflationary spiral.

[maaku]

To further this logic, demurrage allows the effects of inflation but with naturally low interest rates, reducing the probability of a positive-feedback spiral.