Aspiring Lurker (He/Him)
I believe that @Lanefan is presuming the party could have avoided the town. I also expect he is working from a formulation similar to this: Unavoidable traps: not cool. Avoidable traps: cool. Avoidable traps that rapidly reduce the good options available to the party: really cool.We have different ideas of cool. Unavoidable traps with nothing but bad outcomes don't make my list.
I think, though, that this might be one of those things that is clearly on The Adventure Path (and therefore really hard to avoid) that then works to rapidly reduce the good options available to the party. Players accustomed to Adventure Paths might (correctly) intuit that they're "supposed to" go to this place, but not have any idea what's there until they get there, at which point their options start dwindling rapidly. So, a trap that the party in principle could have avoided but in practice figured out they weren't supposed to. I think that's even worse than one they couldn't have avoided, personally.