To the extent that financial innovation makes markets more complete and more efficient, actual and expected changes in official interest rates are readily transmitted to a wide range of financial assets. Overall, the effects of policy decisions on financial markets are stronger and faster.
This is particularly the case for products issued by banks, such as FRNs and corporate loans. The counterparties to these products would still need derivatives that reference BBSW so that they can hedge their interest rate exposures. It is also prudent for users of  any benchmark to have planned for a scenario where the benchmark  no longer exists.