The problem is that a lot of the times, the only way to get a game is to get it used. The real culprit in the whole used game outselling new games in the publishers themselves. If they cut the price of the games they would be more appealing, if they made them available for more than three months until th eonly way you can get them is by buying it used. Castlevania games are a great example. In about 5 months you probably won't be able to get Dawn or Sorrow or Curse of Darkness new anywhere outside of Ebay or some obscure store.
I for one only buy used games if I can't get them new. And the 5 dollar discount that Gamestop.com and EBGames.com sell used games as opposed to their new game counterpart is not an incentive to buy because even if the game is only a month old, you will run the chance of not getting the case and instruction manual. And five dollars really doesn't cut it either, anyway you look at it. It it were like 15 or 20 dollars cheaper them yeah, maybe, it would be a good thing to look into.
And then you look to next generation where games are going to sell about 10 dollars more per game than the current generation, used games are going to evenmore important because that extra 10 dollars you will be paying isn't going to be for extra content (some cases, yeah, maybe, but on a average game, no.) so you are going to be paying 60 dollars for a game that you used to get for 50 dollars and people who don't have a lot of money to spend on games are going to be taking a closer look at the prices. And parents, who I think it has been proved, (not sure though) buys more games than any other group is going to look at the price and probably won't buy as many games for their children anymore. That extra ten dollars can go for food or clothes.
I think next gen used games are going to be more important than this gen.