When interviewing, you receive first person information. It allows remarks and questions to be answered correctly. In media writing, interviewing gives the writer room to be creative with their questions. When asking the right questions, you have to be careful. You never fully know how the one being interviewed will react.
Personally, I believe the best source is the direct source. You must be able to gain information from the interviewee. A lede is hard to come by when going to other sources. Sometimes you receive little information or just wrong information. Writers must be careful when directing an interview as well. You must be able to feel the person being interviewed. You must understand that not every story can b e the same. Like Knight says, there is not just one way to write a lede,