I think it didn't CASA long to be persuaded that proper ICUS sectors on commercial RPT operations (where they act as if in command and make all operational decisions under the supervision of a Captain)
Accept it wasn't proper ICUS. All of the significant operational decisions were still made by the Captain. It was just Pilot Flying time logged as ICUS rather than Co-Pilot. The Captains on the flights didn't even know if the FO was logging it or not. Once the pilot had achieved the ATPL and the command upgrade requirements they went back to logging straight Co-Pilot time once again. Based on the old hour logging requirements of half for Co-Pilot time it actually meant that some Co-pilots were logging 3/4 time. Half time for when the Captain flew and full ICUS for when they did. In fact some Co-Pilots requested to fly all the sectors so they could log ICUS faster, until CASA found out.
What really needed to happen was for the ATPL requirements to change and reflect the fact some pilots will go directly into the RH seat of an airliner and never gain command experience until they are given a command, but that that is ok as long as they have the significant FO time to back it up before hand.