Personally I have never bought a second hand game and very much doubt that I ever will. I buy a huge amount of games, most of them on release and have a collection approaching 300 games. However, my thinking when I buy a game is that if I do not like it, I can always sell it after having given it a spin (though I have to say that I have never traded in a game). I have always believed that if a product of any description was sold more cheaply, that more of that product would be sold in the first place, as more people could afford it. It makes sense that if a person is prepared to part with £20 for a second hand game and then a further £10 for a Season Pass to replace the one that was use when the game was initially purchased, that they are will be willing to part with £30 to buy the game new thus enabling all the money to go to the developer. Ultimately I believe that if developers sell the games more cheaply, they will sell more and quite possibly make still more money once all sales have been made than they would if they stick to the higher price.
It is quite wrong to prevent people from selling a purchased item once they have finished with it, and I can think of no other product that does it; once you buy the product, it becomes your to do with as you please. From cars to CDs, DVDs to toys, all can be bought second hand, no other product seems so fixated with the second hand market as games developers. I strongly believe that developers will suffer a significant drop in sales of new games if purchasers of new games cannot rely on being able to sell them on; this could be the kiss-of-death for game developers, as the majority of people that trade in games, do so to buy a new game. Kill the second-hand market and you will put less money into the pockets of the very people who keep the games industry afloat.