Well the idea was that the Engines were somehow transforming and adapting the Earth to Krypton's much heavier gravity.
Why exactly that required all surrounding objects to be lifted into the air and violently smashed downward, I have no idea. But it was bound to be a destructive process one way or the other, and they clearly had to make this process visually interesting and dramatic for the audience, so I don't have a problem with it.
And to suggest that the falling buildings and epic destruction were only there for "entertainment value" just seems silly. It was clearly meant to demonstrate just how scary and powerful and dangerous Zod and his men were, and to give Superman an overwhelming threat to overcome-- because Snyder and Goyer clearly felt that Superman required
a much bigger threat than we typically see in a superhero movie.