There's also a psychological benefit to page numbers. If I know I only have 20 pages left in the chapter, I am much more likely to finish the chapter before putting the book down. However, if I know I have 10% of the book left before I finish the chapter, I have no way of knowing what that means and therefore am more likely to put the book down for the day. With locations, it can be even worse. If I have 500 locations left in the chapter, it can seem daunting.
I know some people will argue that if I were a "true" reader I wouldn't care about petty things like progress. But, in reality, our minds do care - whether we like it or not. I consider myself an avid read (I've finished 16 books so far in 2012, 15 of which were non-fiction). But the more I can wrap my mind around the progress I have to make, the more I will read in a sitting. Page numbers help me do that.