Blade Runner

Much like the movie Blade Runner, I wonder if they added Fishburne's voice over late in production as they worried audiences wouldn't follow the plot or empathise with the protagonist without it being explained. What would the movie be like without the voice over?
The scene where he had to murder the opponent drug dealer in the toilet also reminded me of Blade Runner - Deckard's emotional struggle at having to execute life like replicants for his job.