Nafe: I guess I might have felt the same if I'd known about that when I bought it, but I had no idea. That said, I generally don't give a toss for DLC so I don't know that it would have prevented a sale. Nevertheless, it is a bit crap but personally I feel that the lack of DRM beats lack of DLC.
Wishbone: Except when content that was planned as part of the full game is deliberately cut out, so they can get you to pay for it as a separate DLC later.
That never happened with this game. Word on the street is the ending for the game sucked and they were getting so much hate for it that they decided to close it off in a way that people enjoyed.
But what you're talking about happens mostly with fighting games these days. There will be content on the disc that's just invisible, and you pay the equivalent of $4.99 to download a 105K file that unlocks the content. It's hella shady, and it's making me question whether I want to get Street Fighter IV, which should not be something to question. Damn DLC devilry, keeping me away from seeing the Sonic Boom in all its' 3D cel-shading glory.