You create a complex NPC with a full plan, but the PC are in a murder hobbo mood and just kill them,
Then you have Bolin the Goblin, who suddently beg the PC for mercy, and someone wants to spare them, so now you have a whole session role-playing with Bolin the Goblin
Even worse,
You create a complex NPC with a full plan, but the PC are in a murder hobbo mood and just kill them, Then you have Bolin the Goblin, who suddently beg the PC for mercy, and someone wants to spare them, so now you have a whole session role-playing with Bolin the Goblin