Let's put things on perspective. TV is a different medium from print. When presenting information on TV, the information presented has to be compressed to fit the limited time. This is where the soundbite comes in.
I don't tend to disparage the resource persons presented in such shows. They all earned their degrees. The real problem lies in the questions presented before them and the length of time they are given for them to answer. Thus, they are forced to issue a soundbite.
In print, authors and researchers have the luxury of space. When we read, we focus on the book. This doesn't happen in TV with all the channels competing for our attention. Thus the shows have to be "packaged" and often "teasers" designed to attract our attention to a show exaggerate things. Thus when we watch that particular show, we feel let down. Also, we have to remember that we all have our instinctive biases based on the books we have read. I've worked in TV before and the pace is just hectic. There's never enough time to put in everything we've researched or worked on. The usual result is a short cut with emphasis on making things visually appealing. That's the weakness (and strength) of documentary TV.