The "why" answer is probably that in CASA's rush to make everything ICAO compliant (must be more than one bonus resting on that) we're now doing lots of stuff that is inappropriate, or was justified on hypothetical "safety" basis (because it doesn't cost CASA), or was someone's bee-in-their-bonnet, or sometimes just a mistake or typo!
The thrust of the CASR/rewrites seems to be ICAO-compliance and bee-bonnet syndrome, combined with a huge dose of legal-branch - then claim that "industry is not ready" when the various drafts are appearing (with substantial changes) only weeks before the regs became active! Don't blame industry, we were not ready because you were unable to tell us what to get ready for (part 61, I'm talking about you).
Enough bitching about the past, now if CASA were sensibly overseen by people who knew what was happening, then we could start cleaning up the mess...