All the storage technology up to date are 2D based. That means in order to store large amounts of data, you need a large surface area, hence the harddisk platters and the optical discs.
Granted optical media now have several layers stacked on top of one another, so you now have multi-layer discs. But still that is based on a 2D concept.
Now imagine you use 3D shapes to store data. Now you can cram a large amount of data in a very small volume of space, and you are no longer restricted to storage media with a large surface area, you can make it any shape you want, as long as whatever data retrieval technology you use can adequately access the stored data.
So a holographic storage media in the shape of a block of crystal perfectly suits my needs.
