My view on this (being long time MMO player)...
MUDS, MOOs, mushes and the like needed community to survive. From their humble origins did many of the original MMO players come. Asheron's Call, EQ, Ultima Online, Meridian 57, and a few others made of the 'First Wave'. You helped each other 'cause you had to. In many of them there were no 'quests'. You went out and killed stuff, hoping for a good loot drop. Many had item drop or loss on death. You NEEDED to have friends on the off chance that you needed help with a corpse run.
SWG, later EQ, and many others came next in the second phase of MMOs. At first they were similar in design, and yet the community aspect was still there by necessity. Quests were still limited in scope and number, and player made (and driven) content provided some of the most memorable experiences of the game.
WoW brought upon it the sundering of the genre. Detailed and in depth quests, instanced dungeons, and many other changes. The stronger guilds continued to foster community, but as a whole the concept of community in an MMO suffered. Other games released during the WoW era mostly failed outright, or resorted to cloning the formula WoW had thrust on us. Community became less important, as you no longer needed help to survive. Death no longer had any real consequences, other than a small exp hit.
We are currently in 'The Splintering' when it comes to MMOs. AAA titles feel the need to be the next WoW killer. Investors demand it. The industry has in turn crapped out a slew of rancid bloatware titles over the past few years, each with the claim of being the WoW killer, while all the while ignoring the community aspect, the part that puts the M's in MMORPG. Cross server queuing has hurt the sense of community, as has sense of accomplishment, being and achievement. We have nothing as a community to loose. For comparison, check out the EvE online community. Once you get past the single players in an mmo, you'll see a true example of a thriving community. It's due to the real sense of risk versus reward their system has in place. If you want to access some of the more remote and higher reward zones, you need to get friends. In most other modern games, all you need to do is wait around in a queue.