I think we can safely say that there is a right way to do DLC and a wrong way.

Clearly if its on the disc already, that's silly. And, if it's part of the main story, that also may be silly.

The game needs to be complete w/o it. If it has others in the franchise, it needs to have a similar amount of content as the others. Which Nintendo made very clear because they knew people would be spazzing out over this.

They wouldn't of been released otherwise...

They solve the problems they have, or at least that make it to the developers. 

It's just that qualicty control practices kind of suck,  not enough time, and not enough attention, so this stuff doesn't really get caught.  Even the big stuff.

What the OP said

It's up to the gamer to buy either :

1) The game and the DLC (aka the game and DLC is good enough for me to pay 70$)
2) The game only (aka f*** DLC, game is good enough)
3) No game (aka I don't like this attitude, I won't pay for this !)

I don't see the problem here on a publisher's point of view. If it sells they keep doing it.