Higgins talked about this years (a decade?) ago. That it feel important to Dick's origin that his family, like Bruce's, was victim of random violence.
They weren't targeted, they weren't chosen, just passing by like it could happen to anyone. And he did his best effort to incorporate the entire "Gray son of Gotham" without altering that aspect of the story.
Right now it feel like edditoria is playing Jenga with the characters, seen how many chunks of the base they can take to put in top before the whole thing comes crashing down.