Having a profile of the man would be useful. It's likely not difficult to see how an old, lonely, man was broken down and fell victim to a silent rage. His inner demons were legion, and this massacre was the ultimate expression of his pain. For that is what we humans do... we share our pain and our misery with others, spreading it like a disease.
And so the most useful purpose of examining the shooter is to ask ourselves, what corrupted him? What sort of society could have engaged with and helped him earlier in life? People are not born as mass murderers. They break down into one. We ultimately failed to prevent that corrosive process, but what if we could?
Maybe what this country needs is an engagement with its citizens... for its citizens. To embrace and help one other - and leave no one behind.