Bill Higgins looks at the Uncanny Valley of UI design. The Uncanny Valley is a hypothesis about human response to an almost-human robot. Bill tries to use the same philosophy in UI design and explains with some examples.
If the design does not fit our mental model we seem to reject it. A designer should keep this mind while designing, especially while introducing new behavior. Even though correct, better or more accurate, it can invoke repulsive emotions from users. Anything that deviates from the mental model requires a learning curve for the user, which can be the cause.
However, I do believe that the deviation will be required, to break away from the usual to explore the new avenues. Only a new thing, like the Web was, can build a model in the first place. Sometimes this can break the mental model that a user has, going to the GUI desktops from the command-lines is a good example. It my dealings I have seen that if the user understands and is convinced, the new way automatically becomes simpler. However, the important thing is that it has to be comprehensible. Note that your convincing might not help, the user should get convinced, not by command but by usage.