A couple of reasons. One of the voices is quite grating; again, I love the content, but it's very distracting. The second reason is that sometimes the conversations bog down or get off on tangents and I'd like the option to skim ahead in the text to topics or questions that are more interesting. I fully understand that the podcasts are a free service, and I appreciate the knowledge and the time that goes into them. Having a transcript available, and the ability to search key words, makes the casts more accessible (to me, anyway).