As a local this was probably his first jet ever.
efatnas, if I remember correctly, the captain had time on the A330/340. So this wasn't his first jet ever. Knowing the EK system, he most likely would have started on the A330 as an F/O, added the A340 to be dual endorsed & then done his command upgrade on those types. He then would have transferred to the B777. The other possibility is that he may have done the command upgrade on the B777, instead of the Airbus.
The problem as I see it was relying on the automation to respond to the TOGA command & it not doing so. The reason it didn't respond was due to the system design. While the design solved a number of potential problems, it led to this other problem, as is often the case. Boeing designers probably thought that this issue was covered by the traditional operating technique of having the hand on the thrust levers while speed & configuration changes are taking place in order to get tactile feedback of auto thrust response, but this technique seems to be fading into the past due to a large number of reasons.
The reason he totally relied on the automation for the thrust increase is yet to be confirmed. However, I would not be surprised if it was as simple as 'that was the way he was trained'. You can't go off at the individual pilot when it is the training system that has led him down this path. There may also be some personal responsibility, for reasons I alluded to earlier, but it is far to early in the investigation to have this sort of information to hand. It also may never come to light.