But even though it's not really the hole that got them in trouble in this case (unless the hole intimidated the horse into taking off early) I look at the hole and think it's only purpose is to make injuries worse if they do wreck there. The horse would take off ahead of it anyway, even if it wasn't there.
Take a look at this one, for example... (not from the same event, found it in google). The horse should never be there unless they wreck, and if they do wreck, it only makes the wreck more likely to really hurt somebody.
I just really think the course designers have gone overboard to make them hard. Eventing should be difficult, but it doesn't have to be intentionally dangerous.