Asking the right questions is the first step to selling in the customer's best interest.
Technicians tend to be great at diagnosing the problem but they need to get great at diagnosing the customer. It's not one diagnosis or the other.
The truth is, I was lousy at diagnosing the customer when I first became a tech. Like most techs, I had a ton of technical knowledge that I was busting to use and I wasn't comfortable talking to people. So, I wanted to skip it. Unfortunately, I was getting a lot of callbacks on my work. Many times I fixed the problem but the customer didn't know. He or she saw no value because I left them in the dark. Sometimes, I actually fixed the wrong problem. That's because I didn't ask enough questions to find out what the customer perceived the problem to be.