It was said (by Johan, I believe) yesterday that if they hadn't done the "spritepack for blue coins"-deal those sprites would not have existed at all.
So, no, they wouldn't have been there when the game was released.
The DLC argument was made several trillion times worse however, because it was not made clear that this was the reason the sprites were being sold seperately from the outset. Instead it was 'You can soon buy our game and also immediately pay extra for some nicer sprites'
I would have felt a bit better if when the announcement was made they had said something like 'we have gone gold, but we are still working on some optional extras which we did not have time to fit into the game. To pay for the extra man hours would you pay £XXX for these to download'
I would certainly have felt better.