Balde Runner is fundamentally film noir and the sci-fi is just the setting.
The essential conflicts are human conflicts--not technological ones. You can replace the setting and you still have mostly the same story.
It only works because of the combination of the setting and the story.
Just comparing the two, Deckard's role is to be a witness to Batty's dawning humanity (as well as Rachel's I suppose). I think that's one of the things that gives the movie the feeling of extraordinary redemption at the end. There's no such sense of redemption in Chandler--the Marlowe storylines revolve around the struggle to keep a moral compass in the midst of societal corruption, in line with the common definition of the Noir genre. [0] (I'm thinking particularly of The Long Goodbye but it's common to all the Marlowe stories.)
Just my $0.02. It's definitely fun to think about.