It isn't a conspiracy, it's a marketing tactic and a very realistic one at that. Bungie promised a product within a contracted timeframe and made the game. When it got nearer to the deadline and they only got 80% of it finished they whip a few levels out and label them as the DLC instead, giving them time to finish the rest for further DLC. It's all very simple and is how big companies work.
When people say "ohh but the levels were empty and there was no enemies so it clearly wasn't finished" it's just because they don't understand how games work. The only reason no enemies are spawned is because the pre-requisites haven't been met. You need to click the level from the map to begin the mission in order to spawn the first enemies and then complete various checkpoints to further the mission. You can spawn into the vault of glass through the door, or follow a team in while you're on patrol but you won't get any enemies and you'll be stuck in an empty environment. Doesn't mean the Vault of Glass isn't finished now, does it (not including the various bugs that need tweaking to the pedantic lot out there)?
I agree with most of what you've said but disagree slightly here. For me, i'm utterly convinced that bungie had seriously intended on taking a lot longer to finish the game, and somebody, be it senior management or the publisher, reigned them in and told them they had to get something ready to publish on November 2014 and if they couldn't make that deadline with their current vision of the game, then that vision of the game would have to change.
By all accounts Destiny went through about 4 or 5 different iterations in development, each time getting scrapped and started again. The current vision of the game was put together in less than a year and was quickly hashed together with lots of content that was originally envisioned left out.
I disagree with the idea that they got to 80 % complete, called it a day and released the game, then finished off the last 20 % post release and sold it as DLC.
For my mind, they had lots of lore / story / content / missions etc.. in mind, but released the game with much of it missing. Not because they got to 80 % and called it quits, but because they had got too ambitious and had to get a game released.
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