Giving a chatbot brain to an NPC who would otherwise only get a single generic line to say creates an infinite amount of negative possibility space. A player can waste a literally infinite amount of time probing a chatbot NPC for narratively interesting details, and all they'll get is chatbot slop. Now it doesn't matter if you put something interesting at the end of the hallway: You've wasted so much of the player's time now that they no longer trust you to. They assume you're just wasting their time. You teach your players to be cynical and incurious and to engage with your work as little as possible, because in their experience it's mostly meaningless.
For this reason, I consider the integration of chatbots into video games to fundamentally anti-artistic. It actively pushes players away from the work such that they get less out of it. Nobody wants this, actually. It sucks.