Avery nice thread indeed. Well firstly i d say that questing in mmorpg is different than in single player rpg .
First of all we must see the truth of our experience and admit that we were not discouraged by kill ten rats quests in the begining of our mmo gaming .
Because it was a new world for us and we hadent tried these ''tasks'' before. Today we are fed up with it as we are fed up with the dullness of mmo rpg fantasy games.

In mmo games devs have to keep the players involved all the time . Even when they are not playing their game .They want them to shave in the morning and think about their game ,eat and think it and so on...
Unfortunately the only way to make them do that is by mainly giving them the vision of being strong and powerfull , by being max level .By letting them think that they matter .When they get bigger and stronger they will be known and so on and so forth .
What is really sad is that the way they found to empower the players is by trivial errands.
So , keep them involved ,breast feed them the dream of power and glory and achieve that through '' labour gaming '' or the endless slave grind as i would say . (No health benefits and pension programmes )

I dumped most games for that reason . When i played for instance Baldur's gate . I had a tremendous story line , fantastic characters to relate to ,intrigue , backstabbing, turns twists darkness light and so on . I had to fight dragons ,lich ,beholders ,dark elves ... It was the roller coaster of rpg's ...
When a compelling story as that transformed into code and game boom! it was a success. So for me it all starts about the story line and how do you keep people involved . Ofcourse with the mmo difficulties and mechanics (single player is far easier ).
I suggest to enrich with story line ,options and imagination . So an errand in an mmo would be go to the dark tavern eavesdrop on the bad trader who has a connection with the dark brotherhood that has a connection to this .Or go and with diplomacy meet him and get him drunk . Ok . These options are difficult to programm .
I really don care if something is difficult to program or not .I am willing to pay more for something that doesnt exist .


And secondly .Make Quests interconnected and bigger .

I would add a third option . Give the players who do not wish the road of battle all the time an alternative.
Make quests about crafting and taming ,hunting or writting books .That in a way they will contribute to the main story line .Meaning professions apart from classes.