It really winds me up when game makers complain about the second hand market
The problem is the retailers. Their focus is mostly on pre-owned sales because that's how they make their biggest profits. Get gamers to trade in their games for a fraction of the new cost, then put the game back on the shelf for a fiver less than brand new. Rinse and repeat making a large profit every time.
Of course fewer new games get sold that way, but then it doesn't matter if the greedy publishers don't sell many new games does it?
I work in games. Personally I've got nothing against selling games second hand, or your right of resale (something I'm annoyed isn't allowed with PC games, especially as we rarely get demos to try out on our hardware). But the retailers have distorted the entire market by focusing on used games and promoting them over new. They're essentially pawn shops specialising in video games. And one of the reasons for the decline of PC games in high street retail is you can't sell them second hand due to DRM and CD keys. The retailers can only sell a PC game once, but they can sell the same copies of console games over and over again.
It's ludicrous the way they do it. Imagine going into HMV to buy Avatar on Blu-Ray and you had difficulty finding a new copy, because the used shelves took up over half the shop. Then when you found a copy the sales assistant kept pushing you to buy a used copy instead for a couple of quid less, and asked if you had any other blu-rays to trade in while you were at it. That's the current customer experience when purchasing video games from a high street game store.
I don't think the major movie studios or book publishers would stand for it either if second hand films and books were promoted in high street stores the same way second hand games are.
But I agree, locking off huge portions of the game and selling them as DLC isn't a good way to do it. As a gamer myself I'd much rather they added value by giving free stuff to legit customers - like Valve do.