I want to be responsible for the continuing airworthiness of my own E/AB aircraft.
I know it better than anyone else. I have done more schedule 8 oil changes than any LAME, I've spent more time inspecting and finessing it than any LAME. I have undertaken basic airworthiness training in gliding, and the structure and operation of a a Vans RV isn't significantly different from a Krosno KR03A Puchatek or a LET Blanik other than the fact that it's easier.
Since the builder of my aircraft died six years ago, I am confident that there is nobody else alive who knows my aircraft as well as I do, or who is as strongly incentivized to keep it in an excellent state of airworthiness.
Under the FAA system's treatment of E/AB aircraft (which is not described in your summary, possibly because it's aimed at operators of certified aircraft), I could take on that responsibility. I'd be able to consult with a LAME, who would still need to do a condition inspection annually; but other line maintenance and minor rectification and repairs could be carried out by my own hands, perhaps under collaboration with my local SAAA chapter.
For certificated aircraft: Most GA aircraft are designed to be maintained under the FAA system. Duplicating the FAA system in Australia would be a natural fit, enabling reasonably painless transition of methods, procedures, paperwork, spare parts, and so on.
FAA regulated aircraft are operated at a higher standard of safety with lower injury and fatality rates.
https://www.faa.gov/news/fact_sheets/news_story.cfm?newsId=21274 -- FAA produced a preliminary estimate of 0.84 fatalities per 100,000 GA hours in FY2017.
https://www.atsb.gov.au/media/5773880/ar-2017-104_final.pdf -- ATSB records 21 fatalities in GA in 2016 across slightly less than 1.2 million GA hours (table 2, 2016 trend-estimated), yielding a fatality rate of 1.75 per 100,000 hours, approximately twice the FAA's fatality rate
We can no doubt speculate over many reasons why pilots in a country with worse weather conditions, more hazardous terrain, and no practical limitation on night flight manage to fly the same aircraft approximately twice as safely as Australian pilots, with less prescriptive regulations.
Regardless of the reason, we should be aspiring to be more like them, and less like us.