I know nothing of the economics of the Australia route, other than anecdotal feedback from friends/colleagues in the region, so I stand prepared to be shot down in flames!
The key seems to be the direct service. There is a significant market who will pay a premium for a direct service to the Middle-East (i.e. 1-stop to/from Europe) rather than an additional stop. The A340-500 obviously gives that ability. (I know a number of people who will NOT take the EK stopping service and will only book on the direct SYD-DXB sector).
Many other carriers require a 2-stop operation from Europe which presumably has 2 effects:
- Reduction in ticket prices compared with the "Premium" you can charge for the direct service.
- Unless there are fifth/sixth(???) freedom or codeshares in operation, then an operation via an additional stop often means a reduced load factor on some sectors. (i.e. Operating AUH-SIN-SYD would mean additional costs and reduced revenues if the SIN-SYD sector was not sold as a code-share or similar and therefore operated with lower load factor once the SIN-bound pax have disembarked.)