I have had 3 near misses that have frightened me. In each case I was IFR on an IFR plan and the other aircraft was a NO DETAILS VFR flight. One of these was at 10,000ft and one was while I was in cloud. ADS-B will not improve safety in any of these instances.
The deal in Class E and G is that if you are in VMC you keep your eyes outside.
The expectation that VFR's will self announce (what? when?) is false and the last thing you want is a false sense of security. CASA would be better off by trying to beef up knowledge and airmanship of those VFR that operate in G and E.