[Brain_Thief]

Not OP, but I share his / her perspective. My reasoning is that the act of killing is a serious and irreversible decision that should not in any way be trivialized. Furthermore, a full evaluation of the consequences of killing should not be deflected, distorted, or colored by something like amusement. Since killing is a necessary part of life (others mentioned vaccines, food production, and gardening below) it seems important to foster a sober and cautious attitude toward the act so as to prevent unnecessary loss of life; the "gamification" of death, even in trivial cases such as with the salt gun, does not appear to promote a sober attitude toward killing.

Essentially, my stance is that there is a difference between accepting an action as necessary and engaging with it as needed and making said action fun / associating it with enjoyment. I don't count video games as part of the issue for the moment since, at least currently, it does not seem like the characters and units that populate video games are in any sense alive. This may change, however, and if it does then I expect radical consequences will unfold.