It is unlikely that more "natural" or human-like behaviour automatically makes spoken dialogue systems "better"
- as in more efficient or more well-liked by its users.
The advantage or disadvantage of human-like behaviour is highly dependent on the application.
However, a dialogue system that is coherent with a human metaphor may profit from a number of characteristics of speech that are typically not exploited in current systems designed with the interface metaphor in mind. To mention but a few
speech comes natural to us;
speech is good for reasoning and problem solving;
and speech is commonly used for social and bonding purposes.
