It seems like Bioware is really trying to show gamers that buying a game new, although it costs a few dollars more, allows the developer to offer more content to the consumer. When someone buys a used game, the developer doesn't see any of that money. I'm not going to lie and say that I've never purchased a used title, but with incentives such as these, it makes spending that extra five bucks for the new copy a lot easier.
(Note: BioWare will release its first paid DLC on April 6. They have not yet announced a price.)