It's not like China are walking back the measures they've taken against Australian exports due to our political criticisms.
On the other hand this deal sets common rules for our regional trading partners and the majority of our trade.
Even without India or the US, it's still massive.
Unfortunately balance of power is definitely going to be an issue without India and the US. Even when the agreement was supposed to include all of ASEAN Plus Six, China's influence would only have been countered if all the other nations united against it.
The US failed with Obama's "Pivot to Asia", and Trump outright ran away. Not only by pulling out of the TPP and ignoring the RCEP, he failed to attend a single ASEAN conference, let alone try and provide any form of leadership.
Unilateralism and "decoupling" just aren't actually going to provide any sort of solutions in an increasingly interwoven global economy.