In Superman II (the 1980 film with Christopher Reeve), Superman
takes away Zod's powers by exposing him to Kryptonian sunlight (while Superman himself is protected by a crystal barrier) and then drops Zod into a deep pit
Superman isn't getting his hands dirty, so to speak, but his foe almost certainly would not have survived this event.
So Superman using violence is not exactly new. I think the events in Man of Steel got more attention because (1) they are more hands-on and visceral, and (2) the whole tone of the film is intentionally "darker" and more serious.