Because it's still unexpected behavior, and suddenly losing aircraft systems mid-flight is a concerning event for a pilot. Especially ones related to flight con

Because it's still unexpected behavior, and suddenly losing aircraft systems mid-flight is a concerning event for a pilot. Especially ones related to flight control. That doesn't mean the plane can't fly. But it does mean that the pilot is going to have to fly it differently to avoid dutch roll, possibly flying at a lower altitude. Keep in mind that this is aviation, which is very risk averse (by necessity). Even minor issues are treated as significant.