OliverSmith, I think the problem with that analogy may be that a video game more easily offers multiple-use potential. There are not only explicit levels to explore, but also easter eggs, hidden levels, cheat codes, etc.--all ways the experience is extended. That doesn't really happen with most books--you read it, and you're done. So if you give that away, there isn't a strong motivation to pay because the user has gotten everything they need from it already.
At least that's the way I use books. Also, every time you boot up a videogame, you'll see the screen--so I can see how that's a great idea. But short of putting a reminder on every 6th page, you can't replicate that for the book, and again, most people may not reread it in the first place, giving you only one chance at a guilt trip.
But I suppose, like most things, the world is based on the fact that the majority of people/buyers are honest and believe that the artist deserves payment. The actions of a few should not be able to upset that, as long as pricing appears reasonable and you're not asking a thousand bucks for your masterpiece.