That's the big question that most CRPG's never address. Game designers put quests in for two reasons: to showcase their leet writing skilz and to make sure that none of their expensive content goes to waste. When compiled from that point of view, every quest log will be either a hand-holder or a spreadsheet - or sometimes both.
But that's not what the PLAYER is looking for. When some random guy on the street tells me that his brother is sick, or that he really likes some girl named Evilyn, or whatever, I'm like, "So, why the Hell are you telling me this?"
Now, in the game of course, we all know this is a plot device that we're supposed to follow and it may or may not lead to something interesting. But, even then, I don't give a rat's ass. To a game designer infected with terminal writer-itus, this is a dream job. He gets to write infinite random crap, and he knows that millions of dollars worth of programming will make people keep wading through his otherwise unpublishable prose.
Of course, as the player, none of that matters to ME. What I'm trying to do is explore the game world and gain more power and equipment. I may want to get in good with the mage's guild to learn new spells; I may be tired of caves and want to see the ocean, or I may just need a new pair of gloves. I may want a very difficult challenge, an easy place to pick up soulstones. That's what I want to see in the quest description.
Sure, go ahead and throw in some sob story about how somebody's cat died if you want to. And red herrings are fine, as long as they're the exception and not the rule. But don't make me click two dozen times to hear an unemployed actor bloviate through an interminable cut scene, and don't make me guess which random response you've decided is the "right" one for whatever random turns you want the dialogue to take.
Writers look at it from the opposite point of view as most players: They don't see this as a game that they're supposed to add a little color to. They see this as an opportunity to write a Choose Your Adventure type storybook with a captive audience.