Don't get me wrong, I definitely agree with your points, granted that it's true that new material is being created or enhanced. DLC is definitely a good thing to have.

My earlier posts were specifically aimed at games which releases content based on purchases or being time sensitive when they are already on the disc. For example, in the original Naruto Ultimate Ninja Storm, the support characters were evidently inside since the CPU gets to use it. For us, the consumers, we had to wait months to use it. By the time the 1st and 2nd Hokages were available to people who didn't pre-order (or like me, outside the US), I've already moved on to other games by then.

On the other side, DLC for games such as RE5 or SSFIV were excellent. New costumes and modes, definitely increases the replayability of the games.

So, just to conclude, I'm all for DLC which is developed post launch, but not for stuff already on the disc.