Postecoglou walked away from the job last year after getting his country to the World Cup finals and was replaced by Bert van Marwijk, who oversaw a draw, two losses and a first-round exit in Russia.
The fact that the Dutchman was credited with improving the team in his short period in charge was testimony to the lack of ambition of Australian football, Postecoglou thought.
"We continue to ignore the lessons of the past. It’s our biggest fault," the coach of Yokohama F. Marinos in Japan wrote in a piece on http://www.playersvoice.com.au.
"Competitiveness and defensive stability. These are not positives from this World Cup. We have always done this."
Postecoglou said his ambition after taking Australia to the 2014 World Cup finals had been to develop a brand of aggressive, attacking football that would enable the Socceroos to compete at the very top level.
It was when the support for his project dissipated in the grind of a lengthy World Cup qualifying campaign and he "lost the mandate for change" that he decided to quit, he wrote.
What was needed now, Postecoglou added, was a loud, noisy debate with plenty of new voices to decide the way forward for Australian football.
"If our way forward is to rely on our defensive stability and competitiveness, then let that be our blueprint," he added.
"But we must shed our inferiority complex. The problem with always being the underdog is that it is a sign you haven’t improved.
"We can't fear failure or being exposed. The Socceroo name alone should give us that strength. We should build on the shoulders of those before us, otherwise we have failed in our responsibilities."
(Reporting by Nick Mulvenney; Editing by Hugh Lawson)
