There are a few reasons why tape is an important part of the modern data centre:
First, tape is by far the lowest cost medium for storing data. This means it is an ideal solution for archiving huge data repositories for information that are not regularly accessed.
Second, with the recent wave of ransomware in the past several years, creating an air gap is more important than ever in terms of an organization controlling its own destiny if attacked. Tape provides the perfect air gap in that tape cartridges are housed in libraries and offline most of time. In addition, media can be easily removed and stored offline, completely disconnected from the network, which prevents the data from being hacked, encrypted or deleted.
Third is longevity: as organisations retain data for longer and longer periods of time, durability and long life are key considerations. When stored correctly, tape media can last up to 30 years. In comparison, hard disk drives have a life of three to five years.