Zemo was always a metaphor for the collateral damage caused by the Avengers, and having this scene could ultimately extend that notion.
Additionally, this would also allow us to see the Battle of Sokovia from a civilian’s POV as opposed to seeing it from above through the eyes of a god or a billionaire in a metal suit.
As mentioned, we know him as a vengeful antagonist, but it would be intriguing to see that same person as a devoted husband, father and son.
Like the heroes of this show, Zemo also has the potential to be further developed, and highlighting the day he lost his family would help show a different side of him.