The critical decision was not to call the new decimal currency the pound. The pound was an option: Cyprus already had a decimalised pound, for example. But that option wasn’t taken.
As indeed it wasn’t taken in the other dominions. Canada, for example, went decimal and dollar in 1858. Decimal because My God, do you really want shillings and pence? And Dollar, because they’re next door to Dollarland.
Her Imperial Majesty wished her loyal dominion of Canada not to use the same name as Dollarland, and tried to make Canada call them royals instead. Which is a translation of the Spanish real, and which is also a suitably Imperial name for a currency.
Did not happen. Overruled by the otherwise loyal dominion’s legislature itself.
At the time Australian decimalisation was put forward, and the option of the pound wasn’t taken, Australia was in the torpor of 17 years of rule by arch monarchist Robert Menzies. Menzies thought that Canadian royal thing was an excellent idea, and wished to see it emulated.
We sneer now, we unruly latte-sipping Australian elites, at how forelock-tugging our antecedents were back then. But when Menzies’ successor Harold Holt tried to implement the royal, he got death threats. He backed down, and went with what Canada had gone with: the dollar. Shortly thereafter, so did New Zealand.