Why did Damon and Greengrass do it?
Three reasons, apart from the money.
One, to kick the film ten years forward into the world of Facebook and fears of mass surveillance. Two, to develop the Hamlet like Father-Son relationship between Bourne and his father: was son to blame for his father's death or father to blame for his son's shattered life?
Third, to counter the macho CIA culture of Dewey with the techno-sharp female opposition played by the po-faced but engaging Heather Lee.
So far from flogging a dead horse, the film succeeds in developing the original trilogy in a way that the Bourne Legacy failed to do. And Damon at 45 is just like Daniel Craig at that age: gritty, hardened into himself and utterly convincing. And the brutal showdown between Bourne and French nemesis played by Vincent Cassel is better than the best UFC.