You really seem to be highly exaggerating this issue, this has happened so rarely, the people that actually actively duel outside cities duel with people that want it there, they don't harass players for a match, pvpers want pvp and a good match at that. This game is not yours alone is the answer, you are actively denying people content which actually does not affect you, just looking for worst case scenarios which rarely occur.
Also this game is Yoshi P vision of final fantasy in an MMO, and already has PVP, threads like this tells people of the additional content to have in the game to do in free time, yet you are actively want to deny content? Please tell me how WoW has not died yet through this, the very model of duelling is from there is what people are asking for and its working pretty healthy by a large account, a niche unknown game thats most likely free to play can't say it counts.
Not to mention you just do not accept other peoples reasons, every reason used was adequate. Just as I do not find your reason to be adequate at all, additional gameplay options grows a game and appeals to many types of players just as Yoshi P has claimed so far.
Heck if going by your reason, why hasn't the option to disable other peoples glamours not in the game? Why should I have to see that from other people, it makes the game look like a circus town. Glamours are not integral to part of the game, its a form of content to those that like it to take part in it. And let them, they are having fun but you don't see me making highly exaggerated claims like it offends my moral standards or anything.