after reading the
wikipedia entry, here's an additional observation.
Scott had a guy write a script. it turns out that script WAS a more direct lead-up to Alien. Then Lindelhof was asked to review the script. He made a lot of changes.
I'm going to bet Lindelhof is responsible for making the script more obscure and having the characters do stupid things to add more mystery to the film.
Just a theory, but its based on the track record of Lindelhof's work inducing the bone curdling cry from the audience of "it doesn't make sense! Why?!"