I'd like to see weaknesses and such be procedurally generated, but unique to monster type. So all the hags are weak to oak wood, and the trolls hate honey, or whatever. Of course, right now I think that each individual night creature is unique compared to all the rest, so unless we get one super-successful night creature that takes enough mates and sires enough children to perpetuate itself (a la Dracula), then we have to deal with the odd fact that the peasants somehow know how to defeat the night creature, but are unable to do it themselves.
If monster types do end up being the way Toady goes (or the successful single night creature posited above), then you have the justification that some folk hero has killed one before, and therefore everyone knows the story. This leads to the situation where all the villagers just know that if you carry holly berries around on your person the local monster won't bother you- unfriendly little towns may withhold this information in order to dispose of unwelcome foreigners who wouldn't know the custom. This could lead to the quasi-symbiotic situation where the villagers are afforded some measure of protection from bandits and the like because the outsiders do not know how to defeat the monster, and since this is beneficial to the villagers they never tell outsiders how to defeat it, which helps the monster kill new victims.