I feel they should have had about two orders of magnitude more than that, they're the rulers from the stars, appointed by the emperor, they rule multiple worlds and have interstellar ships, and are some of the most important people in the whole Empire.
This was my biggest disappointment with the movie - they rule many worlds, but it doesn't feel that way from how they're treated. They don't vet even their closest people (like, for real, you don't know your personal doc has his family held hostage by your enemy?). Some mid-level businessmen in Russia probably have better security setup than the House of Atreides; and their posse is more fitting for some aging Hollywood actor. Seriously, they just go move to the new planet, no planetary patrols, border guards, space legions, no nothing - really cavalier about the whole thing, all while fully expecting their rivals to attack. No wonder they got caught with their pants down basically.
In the modern age we don't have much 'pomp and circumstance', but in an aristocratic society that generally tends to be more prevalent. It helps to show people's place in the hierarchy of things.
See for example the "Sir Jean" scene from The Last Duel (set in 1386):