The core of hi tech diagnostics is the ability to scientifically measure a physiologic condition and then to convert those measurements to a digital format for analysis and recording. The result is a highly accurate and consistent measurement.
Traditional methods of diagnosis are often little more than highly educated subjective guesses. To become a good diagnostician requires training, skill and experience. No random man on the street can pick up an explorer or look at a film radiograph and detect decay. However any old man on the street can look at a computer screen and see that the green part is healthy and the red part is decayed.
Since most dentists have spent years developing these subtle diagnostic skills, and they are justifiably proud of them, they tend to reject technology that suddenly makes those skills obsolete. They confuse method with results.