IOT's format has a lot of statements, but not many questions. Bragg doesn't often say "hold on, what are the consequences of that?" (unless it's a prepared question designed to move us through the biography). Ironically, this lack of curiosity gets worse on subjects he understands well (the arts).
The unscripted chat afterwards is often the best bit. I could do with 10 minutes of on-script introduction and 50 minutes of experts discussing something they're passionate about.