It would be a nice benefit but it would also be (AFAIK) a first in the airline industry. At the moment interline issues are handled based on ticket and there is no difference between class of service or status. So anybody gets the same. Changing this depending on status is a nice idea. But I am not sure how easy or difficult it would be to implement this for QF.

What you are experience is just the new reality. Back in the days, airlines checked luggage through with no regards to alliance, tickets, PNRs etc. Then BA was one of the first not to do this anymore and nowadays many airlines won't check your luggage through on two separate tickets outside their own alliance. The problem seems to be worse in oneworld. So LH will check bags through to BA on two separate tickets but BA (and QF) won't do the same the other way round.