Couple of things to point out, that seem glaringly obvious to me.
A modern jet airliner, adequately handled, should never strike the ground with the gear in any position other than down and locked. I have no idea if that was the case here, but purely from the damage it seems it was not?
A 777, in any configuration, has sufficient thrust in all certified environmental conditions, to climb away from a runway. There has been no mention of lack of available engine power.
We are all human. Even the finest of aviators have bad days! I will be extremely surprised if human factors are not a major contributor here.
There but for the grace of God.
Being the carrier it is, it's difficult not to wonder whether other issues may also have played a part, and may continue into the investigation?