Instrument approaches to non certified/registered aerodromes was removed some years back due to the fact that the details of obstacles etc was not reviewed often enough, much to the frustration of some airfield operators.
I understand there is a push now to revisit the approval of an approach to such airfields, perhaps to a higher (circling) min.
It seems that this aerodrome data collection process has been handled badly by Airservices, however the real blame must rest with CASA and those that were responsible for the drafting of 175 (and other regs as well!) in that very little if any consideration is given to GA or operations below 5700kg and the unintended consequences of the poor drafting. One would think that the 'experts' in CASA might consider this in their reviews, but as said above they have no responsibility to foster or encourage aviation
!