>>212690457 (OP)To make it as removed from modern day politics as possible? Otherwise you'd have to feature China vs America or some bullshit like that.
Dune's particular setting is also like a neo-feudalism with no artificial intelligence or robots so they need to explain how that came about, so they do this setting it far off into the future after the Butlerian Jihad and a period of long tech stagnation.
It was the right choice. Alien with its casette futurism and clunky huge computers aged like milk whereas Dune aged like fine wine.