User blog comment:Callofduty4/New Black Ops II Behind the Scenes Video/@comment-92.84.66.233-20120719115040/@comment-92.84.42.8-20120719165319

True, they could have handled it differently, but it was a solution to keep players from camping back and force them to advance. In the recent ones you can just stay back and shoot every NPC you can see (since the AI is rubbish and won't pursue you) without taking any damage. That and the overly nobbified weapons.