Digital technology has blazed forward and usurped analog in only a few decades. Sadly, the one problem it hasn't solved yet is archiving.
Just as books written hundreds of years ago are still perfectly readable (provided they are appropriately stored), film taken decades ago is still eminently playable (given the right storage conditions). We obviously need no special hardware to read old books, while film can easily be read by simple hardware that would be easy to recreate.
Not so with digital technology. There is considerable research on the durability of optical media that shows it is nowhere near as long-lasting as we had thought. And magnetic media is probably even less durable. And even if the media endures, the readers may well not last. Imagine the infrastructure required to read a digital copy - workstation, peripherals, cables, operating system, drivers, applications - all of the appropriately compatible version. To recreate this from scratch would be nigh impossible. And if you needed a dongle then, you will need a dongle in the future!
And what about the file formats used to encode and decode the data? Storing your archive in proprietary formats is making a bet that this proprietary system and all its dependencies will still be available and fully functional indefinitely. That's assuming the media survives!
It is imperative that we develop more durable media in conjunction with open file formats to ensure that the digital media created this century is still accessible far into the future. Competing with vellum and celluloid is harder than it seems...