Sorry, but MEW is quoted by Airbus as 276t (typical empty weight) - that gives a Max payload of 90t. Of course in service the real OEW depends heavily on the airline and the weight they choose to carry for luxury items like showers, bars, etc.
The EK & SQ 777-300's and A380's might both be 3 class, but they are far from being equivalent. The A380 has nearly twice the cabin floor area than a 777-300, so I maintain that IF configured in similar layouts the A380 would carry nearly 600 Pax.
If you redo the calculations for the A380 with 600 Pax you will see that it's much more efficient than the 777 - the size effect.
All this is negelecting the fact that the A380 is designed to acheive more than just minimum fuel burn - Noise for example. It is way ahead of the 777-300 in both external and internal noise (yes I have travelled on both). Some of these additional objectives compromise slightly the fuel burn.
So environmenally friendliness is about more than just fuel burn and ultimately it's up to the airlines how they use the A380 - not Airbus. Today they are clearly using it to offer more rather than carry more pax with less fuel.