The Aloha incident was caused by a series of small fatigue cracks that after a period of time joined together to cause the rapid decompression and major structural failure. These fatigue cracks were caused by a voids in the Aloha 737 fuselage lap joints.
If you look at the pictures of the damaged area on the Qantas 747, there is a lap joint running right through the middle of the damaged area. Could a faulty lap joint have caused this failure, I don't know its just a thought.
However, there is an AD that requires all lap joints to be inspected to insure they are sound. But this is done externally using untra-sonic testing and since the area that failed was under the fairing, maybe the area was missed or it was just too much trouble to remove the fairing and do the test?