Did you read the link? The point is that they AREN'T really worth that much. My brother buys his xbox games (I stick with PC/Steam mostly) from gamestop and trades them in within a week or two if the multiplayer isn't exciting.
So, to him, a game is NOT worth 60 bucks. The 60 dollar price point has nothing to do with him. He pays between 30 and 40 max, usually only playing B rated single player games years after the fact.
Adding DRM isn't going to magically increase the value of a game to the customer. That's not how a market works. The market currently has decided that a video game is worth something per person, on average. Let's call that $40 per game (just an example). So, with the DRM, you sell two $60 games for every three $40 games. Still the same $120 except it all goes to you instead of the first sale to you and the next two to Gamestop.
If MS can assume (or predict, or hope, or whatever) that more of their sales will go directly to them, then they have an incentive to drop the price of their copies of the game because they know that a gamer probably has a fixed budget for gaming and they want to maximize their value.
I don't have numbers but I would be interested in seeing what the average price per console game actually paid by a customer is. My hunch is that the DRM isn't expected to increase the overall sales, in fact they might decrease BY DESIGN. But MS doesn't care about overall game sales. They care about 1st sales. So they might get a bigger piece of a smaller pie and still make out in the end.
Sidenote, Steam's success came from no legit competition, better prices (allowable, in part, by their DRM) and great marketing but I agree that Microsoft's strategy is more likely long term.
....all in all, though, it just feels shitty to have something physical in my hand that I can't really sell to someone if I want.