Because the Great Background War for Control of the X (Multiverse/Galaxy/That Burger Joint/The Turf/Etc.) doesn't mean ANYTHING unless it interacts with the players in some way.

So really the only thing of note would be those changes that [i]actually[/i] affect our characters.

As you described martial law earlier, what differences does it make to our characters? ESPECIALLY the ones who do NOT live in Estermere and would ditch as soon as that happened. Why would they have motivation to stay? Trapped due to Martial Law? It's a reason they'd stay, or kill enough of the guards to get out or help the invaders wreck the place so they can go home.

But yeah, like for the many travelers characters, it's really mostly a cue of "Sucks to be you jerk bags. Have fun scrubs." As why do they care about a town's martial law? 

But for say Elric and townsfolk, it's a damn serious matter being put under martial law, something that usually rarely happens and forces everything to change. So they'd care about the War.

Travelers? Not so much, just try to avoid getting stabbed and get out. And don't come to town anymore.