Day 1 DLC isn't the worst thing ever if it is free. Of course developers would charge for the DLC if you don't buy the game new. If you buy it used form gamestop, THE DEVELOPERS GET NOTHING. This way, they will get a small proportion of the sales of the game from a percentage of the population that get it used. And some money is always better than no money.
Now, stuff being cut from the game, and forcing everyone to pay for it? It can get very muddy. Rock Band did it, but the argument is that you can pick and choose what songs you want, and you don't have to have anything forced on you. Plus, none of the songs were "essential" for the game, it was only for your own enjoyment. Plus, it wasn't a case of a 1-time DLC, we still get Rock Band DLC each week. Assassins Creed 2 does this where
*SPOILERS*
Two whole chapters are literally cut out of the main story as a plot event. Paid, yet still somewhat cheap, DLC will fill those two chapters in.
*END SPOILERS*
Mass Effect 2 did it as well. You got a new mission and a new character, that while interesting and really cool, did not overall affect the story. This is a good way to do it.