Not sure about Airbus but on Boeing be careful about following the non-normal checklists blindly when you have multiple failures. The notes in the back of the QRH say the checklists address single failures. Multiple failures require a bit of thought/judgement.
Also a lot of simulator sessions are quite contrived, ie. multiple failures just after take off (hence very close to an adequate airport) therefore most of the time the decision to return will be the correct. The decisions on how to address the failures may be different three or four hours away from landing!
If you shut the APU down OEI you've still got a main generator and the back up generator. Sufficient for immediate landing? Sufficient to hold and jettison? vs the risk of an APU fire.