Books were once rare and expensive and only the elites or scholars had access to them. Since the printing press, at least, they have become widely available and many people find them to be valuable in their lives. Books can be used for information as well as to stimulate the imagination. Books are also good because they encourage deep thinking. A lot of online information transfer is shallow and superficial. Books, which are generally hundreds of pages, allow more space to develop ideas and require more deep thinking.
As a result, it is useful to read books because they can help us become deep thinkers. Also, books are valuable because they provide a back up in the case of a digital dark age in which all digital information is lost. If this happens, then books will become very important for preserving our knowledge of history, science, the arts, and other realms of human knowledge. Books are also a good way to absorb information while not being in front of a screen and thus is a break for the eyes.