Here is an interview with director Alex Proyas where he explicitly discusses the removal of the opening narration [1]:
BLAKE: What is the biggest difference between it and the original?
ALEX PROYAS: The general pace of the movie is quite different. The director’s cut more or less is the version I had originally sent out when I was first testing the movie. We had problems in testing and it’s why the studio had us add in the voice overs, which I thought was rubbish really! My instinct then was when something wasn’t playing right to speed it up and I’ve never been happy with that, so this version is back to a more leisurely and thoughtful pace it was meant to be. The voice over from the beginning is gone of course. There is also a few scenes added back that were ditched that I think are perfectly good scenes and I have no idea why we dropped them then.
