I think some of it has to do with the fact that a lot of the info that would go into the manuals back in the day now just gets programmed straight into the game. A lot of games not only teach you how to play them these days but give you pretty blatant hints about what needs to be done to complete them. I don't necessarily think the change was for the better - half the fun with some of the old games was figuring out all the little secrets for yourself. Of course, the style of gameplay during the 8- and 16-bit era was so radically different (and, let's be honest, on the whole, less complex) that maybe it's no surprise games walk you through the steps of learning the gameplay these days, but regardless, it does seem like we're missing something these days. If nothing else, the colourful artwork that was often included in game manuals is sorely missed.