Well, yeah, of course if you're just sitting in your living room you'd rather read than listen; however that's not really the use case of a Podcast.

The value podcasts bring is you can consume them during times you can't read. During exercise, driving, walking to work, cleaning the house, cooking, and train/car rides (for people who get motion sick while reading in a moving vehicle). They turn tedious menial tasks into times when you're mildly entertained - that provides immense value.

They can also be used for a slightly more interesting white noise.