Earlier this week someone, who we forget the name of, said something along the lines of: "Hey Game publishers, how about I buy a game for $30 and then gradually build up to $60 with small payments, like DLC". In the latest GameInformer, Epic's Cliff Bleszinski and Rod Fergusson have other thoughts about the use of DLC.
Fergusson points out that, DLC is "less about shipping what's left over. It's not about, 'Oh, we had this map left over'... it's keeping the disc in the tray. In a used game culture that you have to actively fight against, I think DLC is one of the ways that you do that."
He also points out that, "What people need to understand is that extra content is something that you have to plan."
Adding to the debate in his usual style, Cliff Bleszinki points out that, "You don't just lift up a rock and say, 'oh shit, there's new levels!'"
Source: Game Informer via CVG