I think the whole "But games would be cheaper" argument has been put forth many many times before, and that's just not how it works. At the beginning of the age of digital distribution, this was one of the main arguments in favor of it. "Since they don't have to produce physical copies, the games will be cheaper". Did it happen? No. In fact, digital copies are often more expensive than physical games, sometimes quite a lot more.

The fact of the matter is that games cost as much as the market can bear, that's the long and short of it. Because when a corporation has an opportunity to cut down on their expenses, they see it as a way of increasing their profits, not a way of lowering their prices. So if publishers were to "get in on the action" of used game sales, the one thing you can be damned sure they wouldn't do is to lower the prices of new games so that they made the same amount of money as before. No, they would want to pocket that extra money, because they're businesses with shareholders who expect the maximum possible return on their investment.

In short, I think the "games would be cheaper" argument is terribly naïve. The only thing that can drive down the price of games is competition. And publishers generally don't compete on pricing, because they all have a vested interest in keeping the prices as high as possible.