After browsing the forums, I see that the developers are against adding a "delete quest" option. I understand the rationale; however, there are those of us who are "type A" and like to see a clean slate - and some quests, regardless of intent are not fun for some folks to do [example for me - quest line from Gloria Kendall to get some clothing - don't want the gear because I have better now].
What about an organizer of some sort that hides quests in your log? Maybe something that you can prioritize / rearrange quests as well?
For those of us who like micro-organizing and studying our options, number crunching ... whatever ... this would be a welcome addition.