Two of the corporations involved in major book scanning have sawed off the bindings of modern books to speed the digitizing process. Many have a negative visceral reaction to the "butchering" of books, but is this a reasonable reaction?
A reason to preserve the physical book that has been digitized is that it is the authentic and original version that can be used as a reference in the future. If there is ever a controversy about the digital version, the original can be examined. A seed bank such as the Svalbard Global Seed Vault is seen as an authoritative and safe version of crops we are growing. Saving physical copies of digitized books might at least be seen in a similar light as an authoritative and safe copy that may be called upon in the future.