I would make an MMORPG, where there the game world is persistant. Where a quest can only be done once, and by a single party/player. Also the game world should change and evolve over time as quests are done. Players will come to understand that their actions affect the game and the world they inhabit.
Permanent PVP enabled, this to make enable people to interact witht he enviorment and other players. If the player cuts down another player, it will have consequences, same again if the player cuts down a NPC. Depending on how and where it is done.
Crafting should have an enviormental impact. The caprenter needs wood he gets wood from a forest by cutting a tree down, the stup is left and new trees eventually grow up to replace the old one.
The world and the PVE elements challenge rating would be permanent, meaning that a Dragon or a goblin is the same difficulty level where ever you meet them. This gives the world consistency and players get to understand and know PVE elements based on their play experience.
The PVE elements would be found everywhere and at anytime, meaning that you will at some times meet weak PVE and at others overwhelming ones. This is to encourage party building. Where as the single player can survive a group can thrive.
Skill and ability based system, where chooses skills rather then classes. Where the skill maximums are govorned by ability score.
Moral based combat system, meaning that a player whoes moral has been depleted runs away automaticlly, if they can, or is killed if they cant. Penealty for dieying should be harsh, loss of skill.
Tactical movement, and fast combat. Usable enviorment, need a baricade, cut down a tree, move stones. Less dramatic terrain, movement over terrain should be realistic, no more speed climbing 82 degree slopes.
When character dies, all gear is left behind. Gear should be utilitarien, not game breakers. Skill and experiance should trumph gearheads.
Mounted Combat, knights where masters of the battlefield for a reason.
These are just some of my ideas for a great MMORPG, in short I want it to be more like real RPGs, then todays, MMORPGs. Today an MMORPG is more socialgaming then real RPG. There are few if any moral choices. Quests have no menaningful purpouse beside the harvesting of XP for grinding.
By making it a much more unbalanced world, you get idiosyncrasies, you get an organic feel to the world. It will evolve and grow over time. Also have the maps huge. Implement fast travel and overland maps, while make the diffrent servers diffrent countries/areas, so you will never have the same place twice and people can move between servers as one travel from one place to another.