It is key to place the power in an MMORPG into the hands of the player. At the moment, MMORPGS are centered around NPCs and their quests. Leave NPCs but make them more complex in their interactions. They are important only as seeds. NPCs do not give quests. It is vital to Drop quests as the focus point of MMORPGs and instead have the players create their own histories and world.
The first step already taken but has need of furthering is the requirement is the ability to exist in a setting with some element of mundanity. A flaw with MMORPGs is that everyone is a hero. Although it is important that everyone feel special there must be some introduction which makes the emphasis of hero a bit less or rather, draws attention away from it. The answer is twofold and the combination of which would result in a enrichening of the player's experience.
The first suggestion already exists in some form in most MGs, the ability to own property and maintain a job. I do not know however, that this is done to full potential. Suppose every player could choose what town, city or village they were born in and suppose everyone had the option to choose to have a house there, then a simple mundane aspect is introduced. It is open whether towns should have a capacity, with maximum preallocated player spaces . Creating a tie, one might expect that as certain cities grow in notoriety, fame and history, newcomers may know exactly where they wish to enter from. The option to be a wanderer must exist. Player vs player is a necessity but is remedied by having a hometown or other loyalties. It is hoped that complex interactions reduce meaninglyss killings to be results of loser road bandits and such. Some method of politics, whereby one might be able to rise to rule a town may be feasible. This is sketched at briefly next. Key is the ability for players to form societies and groups that are recognized by the game. A furthering of the guild concept.
For example an Academy of Mages and Scholars initially centered in cities but certainly foundable anywhere by enough people. These may be seeded by NPCs whose positions are then ursurped by players as they become powerful enough. Then researches (spells), agendas (what to do, who to remove from power?), criteria (how to get in to guild) etc could be set by the players. Positions could be lost in death, to be regained from scratch; reating an interesting form of intrigue. One imagines that a player who rises to lord of a town might find help from assasins, mages etc. who in turn may require a favour sometime in the future. The lord could manage, through some interface/mini-game the day to day affairs as trade, tax? or choose to have it automated.
The ability to set forth and build new towns should exist. The concepts of jobs could be improved by replacing silly stat modifieing with a set of minigames whose advancing through allows one to produce better and better wares to become rich. Thus one need not even become a hero, or grind away at monsters to gain affluence. The ability to start chains? Buy larger houses? Bribe each other and maintain influence by funding?
The existance of fan based fiction, FAQs, Wikis and guides shows that players are willing and indeed enjoy writing about their experiences. Thus one might suggest that the taks of some academics would be to write a sort of wiki similar peer reviewed history of their world. Housed in book items with original copies in digital libraries housed in academies. The game might be able to recognize major events?
The game might have tragedies rather than quests. Infestations of undead, harrasment by dragons. Uncharted lands. Player Society Conflicts. In fact it might be worthwhile to purposefully have spells that fail and release demons and similar such.
What happens when all the quests are taken, since when a quest is done its gone for good, for all? I dunno. Whatever. Make new ones? A bad stuff generator using logic should not be so hard. But the emphasis should not lie there but with the player to player powerplays.
An example might be that some player with some help, was able to obtain a powerful relic that allowed him and his cronies to subjugate his opponents. An unbalance? So? That is fun, let the downtrodden be creative and figure someway out. Find another relic (while keeping the search secret and if found avoiding or racing agaisnt the enemy to it) ? Assasinate, inflitrate the other socities? Who knows. Another scenario might be that some fellow summoned a powerful creature. With each total as players succesive cast a probability for a demon to appear or a rift to tear occurs and the land is overriden? Cities can be destroyed and rebuilt? I could go on.
But the key is to have a few simple set of rich rules which in total combine for a highly complex system. In fact...I just realized that one could create and represent MMORPG theory in the language of mathematics where one could predict stuff and analyze complicated concepts more simply... I do not know that I will attempt such, my plate is already overladden.
And that is my take. I know it is overly idealistic since it depends on people but to me this seems as if it would be fun.