[dsnuh]

I believe that the technology in the book must be viewed through the lens of The Butlerian Jihad events of the Dune universe, and the commandment of not making a machine in the image of the human mind. It isn't retro-futurism, it's human-centric technology.

In the later books, shigawire is also mentioned as a data storage method, so I don't think it was a lack of imagination.

[b5]

Herbert quite deliberately planned the Dune universe to be seemingly technologically backwards to remove the crutch of technology and focus instead on human potential.

[dsnuh]

Exactly, and this is why I think the series is such a standout.