Arguably the same reason that the Greenspan put was in place for 30 years (low US interest rates) and why this same flawed approach is being pursued for another decade despite the last GFC:
Almost every person government/council/finance owns their home and maybe a couple of investment properties to boot to it is in their interest to keep the low-interest asset bubble scheme going. Keep interest rates low so house prices don't fall. If that doesn't work then grow the money supply to inflate asset classes at the expense of savers who are in the minority.
Possibly the same reason why land release in Sydney has been so restricted for so long.
Nobody will rock the boat because everyone has a hand in the ponzi scheme.
There is a solution if the state of the world upsets you...
