The pictures around show stripped gears as causing the failures, or one failure anyway. I think the point is that Nissan should have designed in a weak transmission link that is external to the gearbox, or, otherwise limited stress that would likely cause internal gearbox failure.
Having gears as the weak point is not very clever, keeping in mind that the car itself is 'clever' with a host of advanced features and outstanding performance. I think that its reasonable that expectations are high for this particualar car, bet Nissan come up with a fix very shortly.