My guess is to let the dead remain dead. Who you were, your family and loves for the majority of guardians are long gone when you are brought back. For the ones who are still around, the guardian once resurrected has no memories of the life they lost and the people they left behind. They died and have not been reborn, just replaced. The person who was died and a guardian fights in their place with their body. Rummaging around in the past can only open wounds for those who may have been close to the guardian and inspire guilt, remorse, and pain for the guardian looking into a past that is not rightly their’s. So far as we can tell, the light too does not care what you were. While many of those brought back were normal people, soldiers, technicians, fathers and mothers, there are conceivably the bodies of war criminals and serial killers from another life walking around as guardians now too. How would you justify that to yourself? How would you react to discover a member of your fireteam murdered your family before either of you were brought back by the light? I say let the dead stay dead. The person you were died, let them have their rest.