Another BR myth to bust still, is that the Unicorn shots came from Legend. They were shot for Blade Runner, and in the DVD set you can see the clap board with "Blade Runner" titled on it. It is possible however that since he knew he would be working on Legend next, he made it with the double purpose as a test to see how he might shoot Legend.
I know that Ridley was trying to follow the "Film Noir" frame work. Where in the end a big secret is revealed, often with a tragic result. The problem with Film Noir endings is that they aren't usually too popular for "Hollywood" movies (why the producers didn't like it), and the twist ending usually only works with one viewing. Blade Runner works because it gets better in repeated viewings, and our connections to the film evolves each time we see it.
Andy