These assertions do not stack up. Inflation has primarily been low because of unforeseen and unforeseeable global events. Monetary policy in New Zealand remains effective and able to influence domestic demand, and thus, non-tradable inflation. While there is some academic debate about the merits of different inflation targets, few, if any, central banks have modified their inflation targets in the last few years.
Although there is nothing sacrosanct about what particular inflation band or target should be adopted as a measure of price stability, central banks have been reluctant to change targets.