The interesting thing is...
Spoiler!
Apparently I'm reading tonight that Chris Nolan was completely against killing Zod. He told Goyer not to do it, didn't even want him to write the scene. But Goyer convinced him it could be done, and wrote it... and apparently Nolan gave in to it.
I don't know... I think it was the violence of the scene that shocked people. Superman has killed enemies before, albeit rarely.
Snyder and Goyer's thinking behind it seems to be creating a reason for Superman's moral code, not just saying he can't kill for no reason.
Either way, I wasn't completely put off by it. I was put off more by him stealing clothes out of the back of that guy's truck after saving the rig. I thought that was a bit strange. It would have been fine if they'd just cut away to the next scene and he'd somehow found clothes.
http://comicbook.com/blog/2013/06/17...advised-on-it/