There is no World Engine, which means there are no specs that say there has to be preposterous amounts of destruction. What on Earth or Krypton do ginormous explosions have to do with changing the biosphere? Nor does the instruction manual require that there be two parts on opposite parts of the planet, thereby sending Superman off so that humanity can inconveniently suffer casualties he can't be blamed for. Even the people defending the carnage have to strain to come up with a reason why the other location had to be Metropolis.
The bottom line is that the producers wanted lots of falling buildings, because they thought that was entertaining. Good for you if you got more value for your theater tickets. The massive destruction wasn't very entertaining.
The movie gave us a decent Lois Lane and that was vastly more entertaining for me.
And the casualties were not
acknowledged. Was there a single bloodstain from a non-speaking "character?"