I don't understand why Apple won't support Aura Cast already.

That might send wrong signals that Apple has started following standard/common specs.

Back when BLE Audio was first announced, I thought Apple would champion it because it finally extends quality limitations making the microphone quality terrible. I guess they’re content with doing their proprietary thing.

I would like that. I wonder if its something a software update can enable or not

I’d expect their chips to support it by now, but LE Audio, which Auracast is a feature of, requires isochronous streams, a feature of Bluetooth 5.2.