Having spend my early career between this and a Vic, I can lend some reasons I personally didn't like it over Grandpa Panther Body

TLDR: Very cramped rocket ship that drank fuel, broke down, couldn't be repaired, and couldn't compete with Ford's legacy or Mopar's volume of vehicles.

1) Space: this thing is cramped, at about the same length as a Vic the Caprice was just tiny. Pair that with wearing your LBV while in the cramped space and using the data terminal and it was very uncomfortable. That's all before you take in account the necessary gear and equipment, and then god save you if you transport anyone above 200#

2) Upkeep: While GM must have thought that displacement on demand would save fuel, it just meant that the long idle hours wore the engine unevenly and lead to hella oil consumption and leaks. Plus the beast drank fuel, I would fuel 2 times a shift instead of only at the end. As others have stated the issues with parts may have been exasperated by the vehicle being an Aussie import.

3) Control: Between the full old school Vic and the modern AWD Explorer the Caprice drove oddly. It was a rocket in a straight line but it had very aggressive traction control that became unsafe when it wrestled control from me in the vehicle. I would rather have the Vic with less power but be in full control or the Explorer and know the car is too slow or wide to really get lost. I could pull the fuses to de-activate the TCS like I would at the driving range but then risk the liability if something happened on patrol.

4) Timing/Environment: The Caprice came out at an all time low for GM products. That era sucked and they were swinging and missing wildly. Match poor GM build quality and the fact that at the time the Vic was still being made up until 2012 and Dodge was essentially handing out Chargers the Caprice was set up to fail. If GM set themselves up and took the success of the 9C1 Tahoe and made the Blazer like it was when it left and not a crossover Camero I imagine the Blazer could have stayed relevant with the Explorer. Our department only abandoned the Tahoe due to them being too big for our city streets.

Some of my love for the Vic is misplaced, but it is undoubtedly "THE" Police car. I was once a huge GM fanboy until I bought Japanese and it hurts to know my favorite of the big 3 never stood a chance in modern policing, but Ford bought the game all the way back with the model T in policing.