Though human error in the final analysis is very rarely open and shut. It's a lot more complex/nuanced that pilot got it wrong.
Very true. But, any blame will stop before it attaches to the regulators or management. Pilots are convenient for that.
Crosswind approach and landing.
The wind direction was 270 on a RWY23. 5deg off the perpendicular vector (275).
It's back to school for you. Perpendicular means it would be at 90º, so that would need a direction of 140º or 320º. Here it's roughly 40º off so the crosswind component would be about 65% of the wind's strength. So the 28-35 knots they had at the time converts to a crosswind component of 18-22 knots, which is windy, but nothing outlandish.
In an approach such as this, would the right wing be normally a little lower as the aircraft crabs in on approach?.
No. There's no point in being wing low if you're also 'crabbing'. When you decrab (i.e. squeeze it straight), you may need a small amount of bank to minimise any downwind drift, but we're only talking a couple of degrees. The wing has struck the ground because the right oleo has failed, not because too much bank was applied. The rollover is caused by the other wing. From the video, there doesn't appear to have been any flare, so chances are there was no decrab either.
What's the height of the wingtip above ground, and how does it compare with other aircraft.
Low, but it's the angles that count, not the height. Draw a line from the wing tip to the bottom of the tyre, on a compressed oleo, and that's the angle needed for a strike. I expect it will be in the order of 10-12º.
Going back to the wind, the headwind component is 21 to 27 knots. A sudden reduction in the wind (or a swing further right), approaching the flare can rob you of IAS, and badly effect your ability to flare. The counter is a handful of power, but if you've already reduced the power to idle for the landing, the response may not be fast enough to be useful. With low slung engines, that handful of power will also tend to pitch you up, perhaps helping the flare. But fuselage mounted engines would have minimal, and perhaps even an adverse, trim effect (i.e. add power and it pushes the nose down).