obviously not good if one falls off the plane????!! you are talking about major structural damage to the airplane, the center of mass will be completely off and the airplane will fall as hard as a rock.
Also, the engines are pretty close to the centre of mass so it's not a huge deal. Asymmetric thrust will be a problem but the drag situation will be better than with 1 engine disabled! After all there is no inactive engine face catching a whole load of air. And an engine failure situation is already a known situation.
Also, if it had failed as designed it would have only lost one. The other one was only lost because the first engine hit it on the way out. As well as the leading edge of the wing and the slats. The plane was doomed but not because of imbalance. It just could not fly under 270 knots.