Couple of points:
1) I wasn't going to say anything, because I understand the sentiment about DLC that you feel was withheld, but I don't see the difference between it "being on the disc" or downloading it. If it makes you feel better, I guess I really cannot contend that point, but I still don't see how that is the case. Either way, you're paying for content that was developed alongside the game. If that bothers you, it should bother you either way.
2) You're not paying for the data on the disc. You're paying for the game, and the game is whatever the developer says it is. If they put resources on the disc to make the delivering of future content easier, then so be it, but that's not part of the game you paid for.
The reality is, we are in a new era of gaming. More advanced, Internet-enabled consoles have given developers and publishers an avenue for increased revenue. Nothing can stop the movement, unfortunately. And as the above poster said, most DLC is conceived and often completed before a game is released.