The trees being out of sight under the nose is interesting, which might have contributed to a lack of urgency - although the approach of the line of the trees should have been perceptible in peripheral vision, even if they were below the sill directly ahead. From the video, the whole of the flyby appears to have been done at a substantial deck angle, so any visual impression of height throughout the whole pass would have had to have been from the side. It's interesting that the first officer was able to see the pylons 8-s from impact though - distant 30-m-high pylons (which look like they're 3km away on Google Earth) - and nearby treetops are not likely to be at very different elevation angles from 8-s (~350m?) away from the trees. Looking forward, it would be trees all the way from the base of the pylons to the sill, and with the ground whizzing by at 40 feet or so to the side and the tree line approaching, it seems to be no place for a confidence-building visual illusion.
Isn't it all navel-gazing anyway? - the plan for the show presumably didn't have any tree surgery in it, and the arrival at the treetops was presumably at the end of a substantial deviation from the intended plan.
Prompt cutting of the power to the recorders implies a substantial impact - rather more than from twigs hitting the rear fuselage - perhaps a few extra feet wouldn't have made any difference. With more angle of attack, the rear might have been thumped into that conduit-slicer even harder (3 degrees being about a meter at the tail from the center of mass), helping to pitch back down and further into trouble.
Would you agree that the prime human factor is that no-one would ever have dreamed of trying this in a non-FBW airliner? Perhaps the same sort of overconfidence factor that has been claimed to account for the accident statistics when ABS systems were first fitted as options to cars, and the serious accident rate was higher in the otherwise identical cars with the ABS than those without.