They suffer from two problems causing them to be so bad that I can see.
They are unimaginative.
They are tailored to be "accessible to all" which makes them "fun to no one".
Most quests should either be tailored to challenge a specific type of player in my opinion (solo or group, for that level it needs to be challenging).
Quests that are supposed to be inclusive need to be creative to hide the fact that they offer no challenge through gameplay mechanics by having unique/fun objectives. FFXI has plenty of examples of this. Obviously this is more difficult to accomplish though, so the majority of quests should simply strive to be challenging even if that limits their "accessibility".