It isn't important. It's been made important by financiers.
What the last 50 years have shown is that trying to manage an economy by trying to influence the amount of credit is a fool's errand.
Instead we should set that ship free - and leave it up to the private sector to determine interest rates amongst themselves. That means anchoring monetary policy at zero base rates.
Instead we should be rationing firms access to labour by pushing for higher wages with a much higher minimum wage and preferably a guaranteed job for all at the higher minimum wage.
What we need to make firms efficient is reassuringly expensive labour. That way they will use the cheap access to capital to borrow, invest in technology and drive forward productivity - solely so they can use less of the expensive labour.
It's time to get banks, lending, and finance out of the prime path. As the Chinese have.