You're misremembering (or didn't follow far enough to get?) a few things. The spice prolongs life, in a way they are unable to replicate or otherwise export pr

You're misremembering (or didn't follow far enough to get?) a few things. The spice prolongs life, in a way they are unable to replicate or otherwise export production of. Production of the Spice also is devastating to the ecology of Arrakis (nee Dune). The natives haven't tamed the worms - but do co-exist with them. The Houses exploit both however, and the planet itself. The guild navigators value is NOT they can perform computations machines cannot - it's NOT a complexity problem. Some spoilers so I will be oblique, but their ability is tied directly to what the Bene Gesserit are trying to breed. And to what Paul is/his abilities are. It's inherently an "organic"/meat-puppet power - as it is implied it's tied to forebears and progeny... And finally, as noted, there is a deeply held proscription against "thinking machines" due to an... event. This actually isn't HUGELY relevant, but allows Herbert to eschew futorology in favor of his allegory. The story's GREAT :) (especially up to and including Book 4, which completes a full arc.)