Not to knock NPR, because I am a long-time listener. But sometimes softball questions are also because the journalist didn't do their due diligence when it comes to research. Asking difficult questions often means asking explicit questions, and for journalists, these are often the questions they already know the answers to. Then, when the respondent supplies the answer with something off-kilter, the journalist knows where to apply their attention - again, because they have done the research.
All that said, I don't really think the journalist, Mastromarino (who strangely sounds like a wizard), asked softball questions. He had a timer, and he tried to delve into multiple categories. His WotC questions were fine for the time he had.