People aren't expecting the DLC to be ready to go. Because of the disjointed and incredibly brief main campaign, plus general lack of content, that the DLC was unfinished main game launch day content that was repackaged.

It's about how they clearly cannibalized the game to tear out great swathes of content to repackage and sell as DLC. This isn't about a game launching and downloadables were already in development, or the first of them was even completed - this is about very obviously gutting a late-stage product to repurpose and repackage portions of it as DLC to sell after launch. Destiny has felt thin from its first week. Within that first month, people were finding traces of something more, something removed. Destiny promotional materials detailing the development of the game provide us a map of sorts for what they were doing, how the game was shaping up, and what went missing. While "content subject to change" is a reasonable argument against the promotional development materials, never before has an upcoming product changed so drastically within such a short frame of time prior to its release. This should all be examined in the spirit of digital forensics; content found in the actual software and promotional materials throughout its course of development paint an ugly picture of a product that was gutted and butchered prior to the ultimate release of a hollow thing, with portions of it being repackaged to be haphazardly crammed back in for an additional price.