Rebel8, it can be important for ex witnesses to use commentaries, or they maybe can't get past witness propaganda and twists out of their heads. In other situations I would agree with you that the bible can stand alone!! But these witness associations are pervasive.
Once I had to write a talk and it was one of those without any source material. I couldn't find anything, so googled info on the scripture! I felt bad doing this at the time, you weren't supposed to read anything from other religions! But I found a beautiful commentary that sparked the first truly Christian thoughts I had ever had, made me so grateful for the sacrifice Jesus made for us. That talk was the best one I had ever written, and it was'nt too long before I was out of the religion. It was in the back room, second school, but I hope someone was touched by the info as I was!