DLC not only brings in more money, it also helps "actively fight" pre-owned sales, Epic Games' director of production Rod Fergusson has said.
How? By "keeping the disc in the tray", Fergusson told Game Informer magazine (read by CVG).
Because of this, DLC has become an integral part of game development, and something planned months before a game launches.
"What people need to understand is that extra content is something that you have to plan," Fergusson said.
"There are people who think that the first day of DLC development is the day after you launched. That's not the way it works.
"A lot of it is that you have to prepare and plan and manage your resources and your people and everything to allow for that.
"It's less about shipping what's left over," he said. "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."
To that end, Gears of War 3 introduced a Season Pass. This costs 2400 Microsoft Points and buys you the first four DLC add-ons before they're released (two are out now with a third, Raam's Shadow, due on 13th December).
Buying the Season Pass is 33 per cent cheaper than buying all four add-ons separately. It's also a compelling reason not to flog your copy of Gears of War 3 before all four DLC add-ons have been released and you've gotten your money's worth.