Neil saw how shocking scenes in the first game worked for the audienece, i.e. Joel's little daughter getting shot by a grunt, Henry blowing his brains out after having to kill his brother turned infected, you name it, so he decided to go even further, thinking that people would like it cus your gut gets punched right in the feels. Problem is that he seemingly does not realize that dark and provocative content needs to be done wisely, especially if the aim is to make you, the player, feel bad about your actions. Do it right, it works. Do it wrong, it fails.
For example, when making Modern Warfare's reboot, Infinity numerous times nodded at Spec Ops: The Line, promising a dark game with "grey morality", but what came out is another wacky cardboard attraction about evil terrorists and Russians with some shock-content, around which the game carries you by hand and points its finger at things you should be disturbed by ("look over here, piles of dead people! Look here, Russians are gassing civilians! Over here, that fanatic just shot a boy in front of his mother! Here terrorists are killing people! Take a gun and torture that evil terrorist in front of his family, but nuh-uh-uh, you can't hurt his wife and son!").