In the creation of Star Trek Gene Roddenberry wrote the future society as a utopia. There is no need for money, there is no hunger and there is little to no violence inside of the Federation. I understand that there are weapons still - that doesn't seem contradictory to a Utopian society. Why is there a kill setting on phasers though? In a society that has advanced in all aspects, why would there be a need or desire to have a kill setting on a phaser? A setting that will immediately disintegrate anyone it hits. It seems not only counter to the society but completely unnecessary.
Now I am aware that it is used many times in different episodes as the only solution to certain problems but despite that I wonder why it's even a necessity. Some other solution may have worked just as well, but using the kill setting was easier. Also there seems to be nothing keeping anyone at all from getting a phaser and setting it to kill. Considering all of the different species and races they encounter it seems to go against the Prime Directive to even use the kill setting on a phaser. So why does that setting exist?