Let's modify your analogy a bit. If someone has a recording a person starting to eat spaghetti, is it more or less likely that the recording will show them then having a drink of water? And if we instead had a series of comics of a person, and the first one says "I'm hungry," and the second shows the person ordering spaghetti., is it likely that they will then eat the spaghetti? Yes, even though they are fictional. Because apparently using fictional being's mental states is useful for modeling what they will do. In the same way, if the AI is modeling based on human emotional states, then recognizing that those are useful predictors for what will happen helps us predict more, whether or not they genuinely have those emotions.