It happened so quickly.

While analysts and economists had long debated the efficacy of quantitative easing — the central bank bond purchase programs aimed at lowering borrowing costs to stimulate the economy and stoke inflation — the narrative surrounding such efforts is rapidly shifting. In recent months, there's been a growing recognition of the limits and downsides to this particular form of monetary easing, underscored by the Bank of Japan's policy changes announced on Wednesday.

Some 15 years after first experimenting with QE, the BOJ announced that it intends to shift the focus of its policy framework to better finesse borrowing costs by, in effect, anchoring longer-term rates higher, and moving away from a rigid target for expanding the money supply. While market participants expect the central bank to further expand bond purchases and take the rate on a portion of bank balances deeper into negative territory in upcoming meetings, the BOJ's move is a recognition that its daring strategy to dramatically expand the money supply to fight deflation has delivered a blow to the financial sector's profitability.