World of Warcraft had tons of areas included in the initial release that weren't used until later. Hyjal was only accessible through glitching your way in. It was used as a raid instance 2 years after launch, and was fully fleshed out in the overworld 6 years after launch. Silithus had no quests at launch, no town, and the enemies didn't even drop loot. A year later they revamped it with a town, new flight path, quests, and even pvp objectives. Karazhan existed, and even had an extensive crypt you could glitch into (which was never fleshed out or used). Ironforge had a huge area underneath it called Old Ironforge, which was never used. Gilneas, the gates to Uldum, Caverns of Time, Grim Batol, Zul'Gurub, The Sunwell and Silvermoon City all had known locations or even entrances on the world map, but were inaccessible.
I know, people keep telling me Destiny isn't an mmo, but as someone who plays a shitload of mmos, it feels closer to that than it does to the typical shooter. I don't really think anything of it when I hear there's areas on the disc that aren't fully developed or used yet.
Now if you want to talk about the lack of content in the game, or especially in the DLC, I'll agree it's bullshit. They already got my money though. I paid an extra $30 to get the season pass with the base game.
Base game:
20 PvE missions across 4 planets
5 group dungeons
1 raid
10 pvp maps (3 of which are only available in the smaller 6 player modes)
$20 DLC:
3 PvE missions on existing planets
1 group dungeon
1 raid
3 new pvp maps
new weapons and armor for the new level 32 cap
On PS3/4 the base game gives you 1 additional group dungeon, and 1 additional pvp map, as well as a few high end items not available to Xbox players. PS3/4 players get an additional group dungeon with the first DLC as well.