I am not saying that the used games market is bad for the industry. It is just not as good for the gamers as many gamers think it is. Like the traditional used games, the only one who really is benefiting from it is the likes of GameStop. They will buy your 'used' game for way less than they will sell it, and you can only use the store credits in the store itself, meaning that GameStop will always profit.
Also, don't think that you will trick GameStop by buying lots of games in sales and trade it above value when the game goes back to normal prices. If I thought about this, GameStop thought about it too. They will always pay the lowest possible, so once the prices goes down, even if temporarily, they will lower the price they pay back and never pay more for it.
While it seems a victory for gamers that the European Court decided it is within their rights to resell digital products, it is not mean we will reap any benefit out of it. The publishers and developers will make sure they will not lose any money from it, making things like on-line passes, freemium formats and subscription models the rule for all games. Oh, and always on-line DRM, as a way to know that when you sold that digital copy you are not playing a backup you made.
I know I am sounding pessimistic here, but we tend to just analyze things in one perspective. While it is positive the idea of selling digital goods, in a world who is going more and more digital, it can come for a price too high to us.