Except of course he's not responsible for "all those casualties". Anymore than the "escalation" caused by Batman in the Nolan film's means he's responsible for The Joker's victims. And much in the way the mass audience didn't see it that way in TDK I don't think outside of the internet forum/cyber community most watchers hold anything close to such a view of MOS.
Please, whether you hate the film or like it, actually re-watch it and get back to me on how much death and destruction Clark is responsible for. The destruction at the center of Metropolis (cuz it aint the WHOLE of the city that is destroyed) is (for the millionth time) NOT FROM SUPERMAN AND ZOD'S BATTLE BUT A RESULT OF THE BLACK ZERO/WORLD ENGINE GRAVITY BEAM. Superman didn't do that if I recall.
When the actual throw down with Zod starts the one total building collapse that happens is a result of Zod's heat vision. The rest of their fight, no buildings come down (and the reason that there are plenty of buildings standing is cuz again, the GRAVITY BEAM devastates a portion of mid town Metropolis but the vast majority of the city is spared the attack) though Zod and Superman's clash does result in damage to buildings, when Zod and Superman skid one another across building exteriors, when Zod and Superman impact one another causing a large portion of building facade to be pulverized and when Zod throws Superman through buildings right before he and Superman rocket into orbit. But... The buildings, like most of the city are still standing. In fact about the only thing unclear to me is whether the parking garage at the start of the fight collapses totally, or if the damage looks worse than it is. However, unless one is being wilfully obtuse, no, Superman wasn't responsible for any of the large scale death and destruction which goes down before he even arrives in Metropolis, especially since the fight itself, which wasn't nearly as destructive as the Gravity Beam was the result of an alien warrior's promise to go on a genocidal kill crazy rampage.