Makes sense to me, actually. You sell what's essentially the shareware version, then have it contain mechanisms that will download the rest of the game and integrate it once the user goes through an online portal to unlock them. Granted, this is not to say that the pirates will be unable to compensate for the change, but it does make it a little harder than simply circumventing third party DRM mechanisms, particularly if the games which integrate the content have certain mechanics to make this difficult.
To these ends, the best mechanism would probably be to never actually download the completed game to the users, but rather have them access the content through online servers. In other words, the DLC ties together disparate portions of the game content, but is never actually stored on the users' hard drives. A pirate would have to actually find the information in the RAM, save it off, then modify the game source code to come up with a special pirate version that integrates the saved off portions. This is just enough work to be beyond the typical effort expended by crackers. It's not as much fun to crack when, instead of simply circumventing DRM code, it's actually your code that you had to work hard to make that you're giving out for free.
The negative gamer reaction is that we don't like buying DLC, but if you think of it as not being DLC but rather unlocking the full game after playing the shareware version, that makes better sense.