Lonewolf... Investigations do indeed usually reveal one or more contributing factors that combine for the final outcome rather than just one single cause. I've also wondered about your question ".. why were they not able to regain control?
They had 30,000+ feet in which to do so, based on FL selected." The ACARS message at 2:12 seems to hint at an upset with the loss of the laser ring gyro integrity. I wonder how much simulator time on upset recovery is spent by flight crews? Avoidance of those situations is certainly stressed, but when it happens on a bumpy night in the middle of a cell with nothing to see outside the cockpit, that is a daunting task to put on anyone. The question still remains on how exactly they got to that point.