Game buyers aren't stupid, and neither are game resellers. Games that have codes will be worth less when bought used, perhaps significantly less. Any game that institutes a 20 dollar fee to play the last level will be close to worthless as a used game sale. Clearly that is the idea the games publishers are going for. However gamers generally don't have unlimited budgets for gaming. And if I am a gamer that PLANS on selling or trading my game when I buy it to get more value from my purchase, I will definitely take that into account when I am at the checkout stand, and have a choice of games.
Let's look at winners and losers here, that 20 bucks for the code just transferred from me the original purchaser to the publisher. (Since any used buyer will want to deduct the code fee from how much they are paying me.) So I, the original purchaser am the one that will pay the price for the lack of a used market for the game I bought. And if I am a big time trader/seller, which going by the size of the used game market there are alot of us, then that is going to affect how many games I can buy new.
Bottom line I can't see how anyone other than a game publisher is happy with this new idea, not only are original game purchasers losing monetary value, but they are also getting a huge hassle to register codes and download content for something they paid full retail for.
As a side note this must have gamefly quaking in their boots.