I know many people dislike the grind of an MMO but many of us do if it is done right.
Personally i would like an MMORPG that was VERY HARD, by this i mean i dont want to be given a dungeon with a recommended level i would like a random dungeon that you can come across where you must brave it alone or with friends and suffer the consequences if you delve to deep. These dungeons could be HUGE, if you struggle on the first floor don't go down to the second, leave the dungeon and grind to level up, buy gear or pay a mercenary to help you out (other players).
I would like the levelling to be slow and the dangers to be real, if you venture out past an area your comfortable with, expect to fall into traps or ambushes that you have managed to avoid in your "comfort zone".
Even hiding the XP Gauge will feel like a surprise and a Big achievement when you eventually level up, i want you to feel the need to meet new people, form guilds and companionship so you can face these harsh lands together.
If the game was made hard to level and long to grind, the developers will be able to throw out expansions when many people (if any) hasn't even finished the original content.
Global quests is a must in a game like this, e.g. large factions would roam the continents (even the world) scouring for artefacts that need to be brought to an alter which could trigger a huge calamity of sorts that opens up new areas and dungeons for the whole server (i was thinking like SAO where only one person needs to complete a level for everyone to be able to move on) i say large factions, but anyone can find these artefacts and take them to the alter but the likelihood of a lone ranger being able to reach them is very slim.
this is just an idea, i would appreciate hearing everyone's thoughts on this, maybe there are less of us that like a grind than i thought, maybe there are more, what would you add to this or take away (without turning it into a generic easy to beat MMO that loses its spark a few months down the line)