Game A (one-time extra charge for unlockable content): "Buy this game! It's awesome! You will have fun! Comes with extra stuff!"
Game B (carries extra charge per owner for unlockable content): "Buy this game! It's awesome! You will have fun! Comes with extra stuff!"
In both cases, the first purchaser expects to be able to sell the entire game, including the extra content, based on how the game is packaged. At no time is the first-time purchaser made aware of the fact that game B will have lower resale value than game A (for otherwise-identical games) - and *that* is the issue here - the expectation that a purchase is fully transferable. If game B's packaging had a small asterisked footnote - something like 'per-owner charge applies for extra stuff' then at least the first-time purchaser is informed about what is being purchased
In your used movie analogy, unless the DVD specifically mentions ON THE OUTSIDE of the case that special features cost extra for each owner of the physical disc, then I expect most people would presume that the special features do not cost extra - and the same should be true of games. Without that notice on the external packaging of the product, the first-time purchaser is being (some would argue deliberately) misled.