How then shall we define whether or not a game is "complete?" If playing through part of a Mario Kart race and then having it cut off randomly part way through was the most satisfying experience in the world to us, would that not then become complete, despite it not meeting our current standard for such? It would seem then the completion is defined by the value of the product to us. And indeed it would seem strange to define completeness of a game in any other way, because if it isn't defined in some way in terms of value why do we even care about a game being "complete" to begin with.
So if completion relates to value, it seems that the discussion shouldn't be about whether or not a game is complete, but whether or not it is valuable to its consumers. If SSB4 comes out and you say "60$ for that thing that is a freakin' steal!" and you gladly give the money because the offering is easily worth that much to you, how can you come back later and say "I didn't get my money's worth because it didn't include something they released later to complement the game?" Either you got your monies worth at the time of purchase or you didn't, and future events have no bearing on this.
Thus quite honestly I don't care if the DLC is on disc made 10 years before the game was ever conceptualized. If I deem the offering they give us to be smash brothers game to be worth it, then it was worth it. Them then selling this DLC to us for another however much money doesn't matter. Or at least it doesn't if you don't buy it. If you do then yeah maybe that transaction isn't worth it, but that doesn't make the original purchase any less valuable either.
DLC arguments are silly as they seem to be motivated by a fear that incomplete games are now going to become rampant. But the thing is, what DLC hasn't changed is the consumer's unwillingness to buy games that aren't worth the price they are being sold for. With all the *****ing that goes on now about the price of games, I don't see that as liable to change any time soon either. People can make their games not valuable enough to bother with, or even "incomplete", but companies will learn that we don't want that crap, and those that don't learn this will die.
Not wanting DLC to exist is selfish. Its existence takes nothing away from you, but it's lack of existence does take something away from those who would have bought it.