They usually wonder around their towns and speak same things over and over. So do you ever speak to them or do just buy your things and leave for next place?Also not only Final Fantasy but other RPG?
I tend to speak everyone in I-VII, in my every playthrough but VIII-X,XII I just speak some randoms, but not all of them. Also in older SNES RPG like Chrono Trigger and Seiken Densetsu 3 I speak them all, well SD3 I have completed so many times already that nowadays if I play it, I just rush through towns.
Now on my second playthrough in XII, I have talked to more people and got to say some of them have pretty interesting things to say.