Controversial, but getting even further down to root causes, the whole "You've got the same rights as everyone else to go home at the end of the day."-mentality is to blame.
People are starting to make the argument that, "No, you don't. As an actor/representative for the State/.gov (despite Supreme Court rulings on "individuals") if you've got a duty to protect society, then at some point your mission has to come before your life."
I think it also comes as a corollary to the increasing militarization of the police. While they do everything possible in the military to minimize risks and maximize them for the enemy, the mission is deemed more important than the safety of troops. That's the nature of war. If the cops want to play soldier with surplus DHS MRAP's and SWAT gear, then the oaths they take need to be re-examined.
Out of 100 dog "attacks", the one cop that gets bit, or loses some fingers, gets a ripped up face or whatever, if the 99 dogs that didn't really bite keep on living, the benefit to society needs to be weighed.