Ok I am a pretty big MMORPG fan. I wish that the games were different than what most of them are though.
MMORPGs lack substance and immersion. If the game is a MMORPG then I think that a person should not be able to type.
"Hey u, wanna party! We can make mad XP!"
This is not Role Playing. Also these games tend to through you up against the same monster archetypes with different levels throughout the whole game.
"Hey guys it is another goblin, but he is wearing full plate this time."
There are thousands upon thousands of mythological creatures that game designers could draw on to create new advesaries. Now I know that it is a time consuming task to put enough different types of enemies to get you from level one to 70/75. But if I am going to pay $10 to $15 monthly then the least there can be is enough to make it so the game doesn't get repetitive. Also speaking from a Dungeon master (Person who runs a D&D game) I know that it is rather easy to create quests that are different and vary in major ways from each other for characters.
"Hey guys farmer *blah* wants us to go gather *blah* over in the *blah*"
"This gentleman lost his *blah* over near *blah* and he wants us to recover it."
"There are *blah* that have been attacking the border of this village/city/farm/land and this noble wants us to go kill them and collect their *blah* (identifying mark) and bring them back to him."
Ok these quests can only be entertaining in so many ways. And some variety would be nice. Make it so that all the creatures aren't always an enemy, maybe that one village of goblins is actually neutral and the character has to go make a bargain with them to keep them that way, having to make the correct choices in a chat log or using skills in the game. If he fails then only he or his party are attacked by those enemies from then on. That way when you get in another party that goes there you have to explain that you bumbled before and now they hate you. Maybe instead of killing everything a goal should be to observe enemy movements and report back, or just observe/infiltrate an encampment. WoW is the best of the online games that I have played about quest Variety, but they lack enemy variety.
Story line always helps alot to. Don't make it linear though. Make it so if the character makes a choice it rules out other choices, and choices should actually affect the characters experience in the world.
Now a lot of people will say this is to much coding for the game designers and the thousands of characters that come on would be a hard task to have the game world recognize them separately and react differently to each individual player. I refer these people to Neverwinter Nights. Not the best game in the world but with the toolset you could create your own game. I created and played in games that did most of the things I have mentioned above, except for creature variation but that was just a built in game thing that couldn't be adjusted without hacks. I created my own games, by myself and though they weren't long enough to keep you entertained for 6 months of straight play, I only worked on them for several weeks. They kept people entertained for a month or two. As for the ones I played in, there were some that kept my interest longer than FFXI and WoW combined, of course these games were created by 6 and 7 people. So why can't a team of 20 that design a game make a game to the standards that many RPG fans want?