I go to Australia a lot, would sure prefer supersonic if its faster

People visited Australia before commercial transoceanic flight too, I don't see why improvements have to stop now.

There's diminishing returns.

Going from weeks to a day - not to mention cheaper - makes a whole lot of sense. Going from a day to half a day at a higher price and likely a less cushy aircraft does not.

Transoceanic flight wasn't cheaper when it was first introduced[0], it took economies of scale to bring the price down.

Additionally, the fact that Australia is a day away and Europe is half a day away is a major factor in why I have visited Europe a number of times and never been to Aus/NZ. I am almost certainly not the only person like this.

[0] https://airwaysmag.com/today-in-aviation/the-first-trans-atl... $375 flight vs $159 first class by boat https://www.cruiselinehistory.com/1930s-sailing-to-france-fr...

Before the jet age NY-London was 19h. It is significantly better as a 6h flight, to the point where the route is so busy BA alone makes $1B of revenue.

Again, diminishing returns.

With things like airport security, weather delays, ground stops, etc., is going down to 3h worth several times the cost?

The Concorde found the answer is largely "not really".

Sure, but in the context of Australia, we are talking halving 9, 12+ hour flight times, which is a much larger improvement than the measly transatlantic flight.