As an aside to this, I find it astonishing that you even still see packaged games on the shelf. The last couple of games I bought from a retailer were just a carboard box, a dvd sleeve inside and a business card with a download link on it inside that... No need to pay a markup for literally nothing.
funnily enough, sometimes the cardboard box is cheaper than buying the digital download.
I assume a motivations of it are a) to have presence next to console games and b) gift-giving? If there were at least the basic versions of the games on the disc, you could add c) people with slow internet to the equation, but that seems less and less common.
