If people wanted to fly for 23 hours non-stop then there would be orders as long as your arm for the planes that can do it.
Pax's don't want to (at least the eco ones) and Airlines can make more by stopping over.
The ONLY advantage I could see for flying > 15 hours would be if it meant I didntt have to stop over in the US and be questioned by the servants of the 4th Reich