Level-Based Advancement Is Not Good Game Design
In Dungeons and Dragons, level-based advancement makes sense. But, in Dungeons and Dragons you are with a consistent group of people that are all leveling with you and you see a logical progression of enemy difficulty. If you have a new player join the group, most likely they will roll and equal level character. After gaining ten levels, you will not fight normal boars that are considered equal to your level but ten levels above the giant evil demon mage you fought ten levels previously.
In massively multiplayer computer games, levels are an archaic system that causes more problems than it is worth. Levels force mudflation, vertically expanding content (most of the time), content exclusivity, nonsensical enemy progression, and power unbalancing among other things.
MMOs like WoW and WAR have a huge mudflation factor. In WoW, the gear you get from killing an immensely powerful mage in your 20s (Archmage Arugal) will be significantly inferior to the gear you get from defeating an ogre boss in Lower Blackrock Spire in your 60s when storyline-wise, Arugal may have been more powerful. The gear you get from defeating an Old God at 60 (C'thun) pales in comparison to gear you get from defeating a random blue dragon in Violet Hold (Cyranagosa). This is mudflation and nonsensical enemy progression at its peak.
I know I had started that dream MMO write-up, but after some time, my ideas and opinions have had time to develop more.
I want an MMO without a focus on gear and levels. Have boss fights be a test of skill, not a test of "do you outgear this boss? yes/no". PvP would be based on who could better play their class, not who had more levels and more gear. A brand new player could hop right into a dungeon with their friend who has been playing for months.
The thought on most people's minds is "What incentive will people have to do dungeons and quests?"
Vanity items and achievements. That is all people need.
One thing I absolutely loved in Lord of the Rings Online was how bosses could drop trophies for your player house or guild hall (I still need to do my thoughts on player housing blog post). Other vanity items could include special armor sets (in looks, not in stats), clothing, weapons (again in look, not stats), non-combat pets, mounts, and gadgets (think of the special loot from the WoW card game).
It may not seem like that would be a big enough carrot for people, but I think it is more of a draw than you would initially think. Plus the accessability this would add to a game would be huge.
Quests could be seen as just as another pathway to make money to buy these items but it is all about giving players choice. Questing, professions, PvP, PvE, playing the auction house, all should be options available to people. The more options you give players, the more players you can hook.