http://www.reddit.com/r/DestinyTheGame/comments/2jijdh/why_i_think_the_destiny_community_and_bungie/
So in my life time I've played a lot of video games. I've played endgame of a long list of MMOs and was a hardcore WoW raider for a while, along with being VERY into FPS, closely following arena style FPS, such as Halo. Destiny is so great because it's a great mix of the two styles of gaming! However, there seems to be a vastly different understanding of the game between the Destiny community and Bungie. The more I think about it, I think I understand why it seems we aren't on the same page. When I first started playing Destiny and jumped into the main story it felt very much like a shooter. There was a definite Bungie style to it. The more and more I played though the more and more MMO elements I started to see. I began to get excited because, hey, I love MMOs and FPS's, so this is a pretty cool mix of both worlds.
Now as a 29 Titan who raids once a week I'm beginning to see the lack of endgame PvE content. It's a lot of grinding, and while I love grinding to an extent, this almost feels like that's exclusively the endgame. So I began to think to myself "I wonder what Bungie thought players were going to do during endgame? Surely they didn't think we would do nothing but grind?" But then it hit me. Bungie develops FPS arena shooters. When they made Halo people spent HOURS playing the same levels, playlists, etc. They're used to that being enough for people, and actually being praised for it. I feel Bungie honestly thought Crucible was going to be the driving force of this game. That's what they've always done, why change the formula of success?
Here's where I think the schism is. While I enjoy Crucible and the arena style aspect of their brand of FPS, the style of Destiny inherently draws us away from Crucible. It has an addicting loot system, which causes us to look for the best way to find said loot. I honestly think it's a clashing between the PvP system and the PvE system. Bungie thought Crucible would keep us happy, where the way the game is built causes us to want more PvE endgame content. The Destiny community and Bungie are looking at the game through different lenses. Hopefully Bungie see's this now and begins to add more content for PvE, because I feel a lot of people are already beginning to be burnt out (not me personally, I love this game haha).
TL;DR Bungie thought the Halo aspect of Destiny would keep us happy, but instead got us addicted to their loot system which was lacking.
Edit: I see a lot of people saying Crucible doesn't have a lot of content compared to Halo, so that couldn't be the case. I'd say the argument could be made that the replayability that Halo had with the extra features was thought to be replaced by the PvE experience (which doesn't replace it.)