There is productive consumption and there is non-productive consumption. In the Keynesian mind, it's not necessary to produce anything, so long as people spend and consume endlessly, even to the point of destroying real wealth.
Central banks have done nothing to end the boom-and-bust cycle. Instead, their unscrupulous interventions in credit markets just prolong the boom. But it's a huge mistake to assume that bringing market interest rates to zero will create a perpetual boom.