The DLC era may even be an enormous bank heist.
I'm in the game industry, kinda, so I want to balance this out a bit by saying: thanks to Gamestop, used games are a strong market, and game companies tend to make some absurd percentage of their sales through preorders and immediate purchases. They need extra revenue. Believe me-- it's in the best interests of the gamers AND the developers for games to have more methods to bring in income than just those first sales. If they don't have those methods, publishers will ONLY invest in safe blockbusters.
DLC can be done WELL. A lot of the DLC I buy is for games that were already massive in scope, and so I don't mind buying "extras." I have definitely bought DLC that was not worth my money, but I've also bought some truly phenomenal additions. The DLC presents a new medium for developers to work in; it's like a "short story" addition to the main game.
I'm not saying you shouldn't buy used games, but nobody's forcing you to buy DLC, you know? Games are self-contained without it-- if they aren't, you have every right to complain, but I've seen no game with DLC that was necessary to continue forth the main story. It's all gravy. Sometimes delicious, delicious gravy.
Indeed, scaling-back graphics in exchange for content is a possible solution, but the gaming press won't look very kindly on it.
It's absolutely true, but there's hope. Take Fallout New Vegas, a game whose merits mostly lie in its story and atmosphere and characters. That game was panned for being backward in terms of graphics and full of more bugs than an ant's nest, but it still made numerous top 20 lists, often with reviewers saying that the game was important in spite of its technical failings. That's progress, I hope!