I've seen economic arguments for DRM, but those fall apart the instant the game is cracked. Why any gaming company would think it's a good idea to sell a product that's inferior to the pirated version is beyond me. At the very least, they could offer a DRM removal tool once it has been cracked, because there's no longer any advantage in selling a crippled game.
//I'll never personally buy DRM-laden games unless there's a crack available. And if the anti-used game thing goes through with the next xbox, I'm definitely not getting that.