Part of what changed is the male population hasn't seen the bloody side of war. When you're sitting in a comfortable chair outside Lake Tahoe bombing the shit out of the Taliban and anyone else who just happens to be inside the blast range as "collateral damage" it stops being real and becomes another computer game, the kind of Hollywood movie where nobody is ever premanently injured or actually gruesomely painfully dead.
The WW I and II infantry saw that, it was their immediate neighbour. They never talked about the nightmares, but made certain it could never come visiting. It started to wander in Vietnam, Rambo's criticism of the Soldier of Fortune mentality is only too real, it's morlocks like that who pulled the prisoner abuses in the Gulf. Too macho, too gangsta, too computer game, where the dead aren't bleeding on your floor. How many points for hitting a politician in your getaway?