Meh, the argument has been made day after day after day, selling your games isn't bad, buying used games isn't bad, it's like used cars, used televisions, used jewelry, used anything that isn't a consumable.
Granted, the stores that facilitate this kind of trade, well, they're almost all equally shady, but it's only fair to contend that buying and selling used games is fair, as fair as buying and selling anything else.
Now, then, the act of adding in DLC for first-time buyers is the market's response, and a clever response, at that, at least, if enough of your audience has the ability to download the content. Now, for all those people who say screw new, let's save $5, there's a strong counterpoint not to.