Granted in the eighteenth century lawyers abounded and so did the courts to hear cases. In fact defamation laws predated the American revolution.
It was social pressure that put an end to dueling. It wasn't just the loss of life; it was the loss of professional ability and prowess. Napoleon put an end to dueling, not because of any moral necessity, but because he was losing too many valuable officers to the duel. It simply did not fit into his plans of world conquest.
Here in the United States the reasons were similar. Not so much from a war standing, but more because we were losing entirely too many law makers and other professionals to this act of honor.
A polite society no longer needs to defend its honor with firearms. We have courts and attorneys for that.
Home Defense, Police Protection and Hunting
It is true that most of the cases where police are called in the problem has already come and gone. In these instances having a firearm at home is not a bad idea. However, a citizen has certain well defined responsibilities regarding these weapons. In other words you can't just shoot someone because you think they are a threat. In almost all areas of the country the defender has to meet some well established criteria before an act of self-defense can be claimed with any chance of holding up in court.
Also, if home defense is the aim a long arm that shoot bullets rather than shot is not the ideal weapon for defending the home. Bullets pass through walls; both the defender's and his/her neighbor's walls. A military style weapon, for that reason alone, is a risky and dangerous means of protecting property because a very real possibility of shooting the "wrong person" exists.
Killing your neighbor is hardly a polite thing to do even if it is accidental.
It is true that many armed citizens live in rural areas and enjoy taking game to supplement their diet. In some areas this isn't just a pastime, but a necessity. But those who use firearms to supplement the larder also raise livestock, fish, and gather plants. It's not simply an activity limited to firearms and that has little to do with civility. But hunting doesn't really have much to do with politeness.