Great question OP. The analogy I'd use is what my Dad taught me as he's in retail. Think of a link like a shop window, its what the shopper sees first. Now if the shop is in the 'High Street', the main shopping area, then the shopper is more likely to look in than they would be if the shop was in the sidestreet, (the second page etc). In other words, the deeper into the search results you have to go to find the link the less chance you have of getting seen, most shoppers stay on the high street, its only the curious who go into the side streets. This is primarily why it costs so much to open a shop in the high street but the rewards are worth it as you get far more custom, (traffic in the case of search engines) the same thing applies to the link being on the front page of the search.