Didn't know about Ridley's motivation/s, but "Alien" hasn't THAT feeling to me - on any level - don't get me wrong it's an "AAA" movie, just doesn't give me THAT emotinal connection as "2001" (even "2010" it's not so strong anymore)

As for "shocking", some movies keep a level, some are gruesome, time tells if it stays a classic, when the first horror is gone, and only character-evolvement/story remains ...

I think what is the key to this strange "feeling" are a handfull of things: long scenes, minor dialog, brooding music - to transport the empiness of space across the moviescreen ;-)

sure, at the beginning, fast cuts from past to present, can push the transit, maybe even leave open a jump forward at the end ...