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

)?
The vote with your wallet thing is ridiculous as well. My £20 doesn't make a single bit of difference to a multi-million dollar company. They don't care, the only person that misses out is me because i don't get to play with my friends. The best way to incite change is to write coherently, publicly and realistically in an obvious place and hope that you spark people into doing the same instead of "herp durp, this game's *** because it never gives me nice stuff" or even better, a developer reads it and it influences their future efforts.
I've always said that the gameplay mechanics and the online community are what's made this game for me. The amount of hours i've spent doing bounties and other chores is irrelevant as a point of argument, because quite frankly... i stuck the same amount of time, if not more into other titles like the original halo as a child, borderlands, skyrim and various call of duty games along the way. I spent years playing counter strike and that thing was as simple as it gets, but the friends i had kept me coming back for more. The annoying thing is that the other games are better refined overall for a comparatively similar price.