Okay, couple other ideas:
I want the ultimate MMO. Basically, it wouldn't be focused on combat hardly at all. You wouldn't run around fighting random monsters with the sole purpose of getting a bigger sword. Instead, you could do whatever else you want.
I'd want the game in a sci-fi setting, simply because I feel it gives the developers more creative freedom. But it would be set on a planet, and would focus on large, dense cities. Sure, you could hang around the outskirts where it is less populated, but there wouldn't be any huge deserts with nothing in them but little sand monsters to kill. In fact, there would be few (if any) monsters at all. The game would focus more around the actual players. You can still buy weapons and such, but you can only use them in a rather limited faction (more on that later).
There would be lots of other things to do. The game would allow you to live a semi-realistic alternate life - hence, the game would have certains Sims-like characteristics. You can buy a house, decorate it, furnish it, whatever. It wouldn't be as focused on that aspect, however. You can buy property to do whatever you want. The game would let you manipulate a (very) simple programming system to apply to your property. If you want, you can make a simple shop. You can also get more complicated and make a weapon-rental system, or a casino, or an arcade (the game would include several simple mini-games on it, like Animal Crossing), or even make your own mini-game with some more complicated scripting and the physics engine (like bowling, or target practice or something that would take place on the property, instead of in an arcade cabinet). It would be limited, though - obviously, you couldn't cheat and have the players automatically give you all their money and whatever.
There would also be politics. The game would have a legislative system like the one in A Tale In The Desert (never played it, but sounds cool) where players can propose bills and vote on them, to be put in by the developers. You could also run for office - whether locally or world-wide (there would be only one true government in the game). A person could actually be elected president of the ENTIRE GAME. He still wouldn't have as much power as the developers, obviously, but he would have realistic control. To keep the game interesting, a new election would be held every month or so in real time (which would be much longer in game-time - perhaps a year or so).
There would still be combat, but it would be limited, as mentioned above. It would take place in gladatorial-style arenas. Players can compete to become champion, getting rewards for winning as well as getting sponsors. Non-combatants could bet on the matches. The combat would be a deep system using a different engine from the rest of the game, having real-time combat that would be customized - combatants could be crazy power-drill-wielding cyborgs or amazons with electric whips and hoverboards. Whatever they want, there would be lots of choices. There would be different classes depending on how much money you have put into your character's weapons, armor etc., so just because you're brand new and have little cash doesn't mean you'll lose - you'll simply fight against someone who is as wimpy as you. Also, it would be impossible to die - you simply lose the match (there would be different rules according to the arenas).
Oh, and of course, the in-game character would be very customizable - you can be a crazy alien of some kind, a robot, a cyborg, or a human. You can wear whatever you want, and change your clothes at any point in the game by buying and equipping them like in Morrowind, as well as getting face-paint, tattoos, whatever. Outside of the combat as mentioned above, there wouldn't be any experience points or skills. It would all be based on your real skills, such as persuasion, debating, bartering, etc.
The game would come with a built-in forum and information database, based around the game. You could access it from in-game computers, and it would let you discuss things in-character. Here you can discuss politics, read politicians' speeches / debates, get news updates, arrange meetings, send e-mail, whatever. It would all be based around the game. Although the game would not be able to stop people from posting FAQ's and whatnot on the (real) Internet, it would discourage this by instead allowing people to SELL this kind of information in the game.
There would be a lot more stuff that I can't think of right now. Maybe an underground resistance movement (very player-run - no automatic missions). An NPC robot tournament similar to the gladatorial arenas, but with player-programmed and equipped robots that would fight each other with AI (no creator interference allowed). Racing. All kinds of other sports. Hacking. Loads of material possessions. Music. Player-made music.
Basically the game would eliminate the usual kill monsters, level up gameplay of MMO's. Instead it would create a realistic world where you can have an alternate life. Man, that was a long post. Thank you, that one person who might read it.