My quest log is a mess, full of main quest lines that takes a lot of time, that I'll never want to do, and at least one I CAN'T do. Examples:
1. The Young Follower, first sub quest: Debris: collect all the collecibles on the map.
This is one I'll NEVER finish, because I simply CAN'T. I've tried many, many times to find all the collectibles, I have never managed to do so, and I'm sure I never will. Hundreds of buildings to hide behind makes this one impossible for me.
2. Epic Woodyards, first sub quest: Setting the Foundation: buy at least one Epic Woodyard
This is a quest I'll never do simply because it's way too expensive to both buy and upgrade the woodyard. And since it only leads to several new similar quests, I have no intention on doing it. Ever. Dozens of thousands of gems, and probably millions of resources to complte them all. I'll never buy the epic woodyard if the price dropped to 1 fish - it just adds more trouble than it's worth.
3. Maturation, third subquest: Obligation: Invest at least 10 Tomes in one of your Explorers
(Including the similar quest line for geologists)
I've given up on these ones. I have lots of explorers and geologists. I'm gonna give them all some basic skills, but won't continue up on tomes levels. This is because it will probably take years to complete the skill trees for all of them (I'm not exaggerating!!!), and if you don't play every day, it will just be even far worse. And when military unis get skill trees, it will only be more such horrible quests, which WILL add a few more years to complete it all. And I haven't even mentioned gold/resource costs....
Just a few examples, I could mention more.
Conclusion:
There are several I want gone from my log. There is no good reason at all to deny us this option. And if you still say no to this, at least add an option to hide quests, then.
The game is supposed to be fun. Right?