I completely agree with you on what you said. Something similar to what WoW use(d), I think it's called Quester. You have the option to view; current quest locations only, quests that have already been completed, quests that have not be picked-up/done yet, or view all quests in that zone, area, or town. That could be set for any of the before mentioned.
Hopefully some developer(s) like 'Wykkyd' pick up a project like this and have the EsoHead add-on database connected. This way the information updates as the game changes and more quests are added to the game, hopefully from a global database EsoHead creates.
-InfiniteImmortal