I agree. The police officer is doing his job by encouraging the motorist to talk. Those who are trying to hide criminal activity often give themselves away with nervous chatter.
Yet, there is this thing called "freedom from unreasonable searches and seizures" and it comes with legal standards that limit how aggressive law enforcement can be in conducting roadside fishing expeditions. To be able to search your vehicle without your consent, an officer needs "probable cause" to believe that there is a specific crime being comitted.
Since the vast majority of motorists who are pulled over for moving violations aren't dealing bags of drugs or hiding dead bodies in the trunk there is an expectation that you won't be harassed or unreasonably inconvenienced by being forced to sit by the side of the road with a bright flashlight shining in your face and having to answer a long list of questions, the answers to which are nobody's business but your own.
