IMHO, a necropsy and releasing the cause of death should be mandatory on all dogs used for breeding. When you breed dogs, everything about them should be public. The care of the dogs, where and how they live and are cared for, health testing.....everything, including a verified cause of death.
I, not unlike anybody else on this forum, have a lot invested in my dogs and always will. The time, the training and all the work I have done to open doors for therapy work for dobermans, not an easy thing to do, btw.
I am currently researching for my next dog and I think it is important to know why the dogs from any given breeder died. A pattern may develop that may steer me away from certain lines.
When you think about it, any stud dog could sire 30 puppies easily. While health test can give us some information, it's only that the dog was healthy when the test were done, especially when it comes to the heart.
I for one, want and feel entitled to as much information as I can get to make the best decision possible.