The idea behind quest XP completion. Is that it always will provide the player (dependent on level) with a set amount of XP. I would advocate the quest completion XP be a min/max 50-500 xp for completion based on a variation of how difficult said quest would be, as well to what levels were required for the quest. (grouped 1-5, 2-5, 4-8, etc...) This would prevent high level characters from tagging along to carebear low levels, promote group working efficient mechanics, RP for success or failure.
Static quests should also be on a transition basis, closed to those who have not taken the quest, basically a locked area that can only be entered by a group of players fitting the level range who have grouped to take the quest. This may require the party mode option to be enabled, something that I sort of would be against, but would understand the need to impliment.
~ OR ~
The other option would be to have those within the quest giver's area of proximity. ex. So that when Lizuca hands out a quest, only those within whisper range of her, who fit the level requirements for said quest will be enabled to enter said quest location/transition/door etc.
As for the fish bowl idea on why that dragon isn't dead yet... I don't see static quests much different than static respawns, we have boss creatures and areas that have been raided and cleared how many thousands of times.. Alhoon's still there.. the Shadow Dragon is still there, the PIt Fiend is still there.. Jezra ... well maybe you see the point!
With static quests some of which could even end with players acquiring tokens, medals or some honorable mentions, especially if they're quests for the Count for example, or those of the Counts authority. Just a notion, though I could easily see such items being exploited by players who repeat said quest and gain a bucket load of them just for the recognition and IC status. Getting a bit of Quest XP be it an extra 50 or an extra couple hundred at the end of it, doesn't really affect me much, though it does afford a sense of accomplishment when you are working with other players, especially so when you are role playing and then come to the big finale. I've always loathed the kill x for so an so xp routine and loot the corpse type achievement dangle the carrot on a stick type of hamster wheel that DnD builds on.
Probably why I enjoy the RP xp reward system here and a definite reason to why I choose to be more in depth with my RP emotes, as they generate more of a graphic image for the five senses. Instead of just verbal dialogue and single note emotional notes.