By and large, authors hate the query process. It's like you just spent years crafting "the perfect novel," only to be rejected by someone who never read it, who only read your short letter that you wrote in a day.
When I started this, I honestly thought query letters were just a formality. It was only after I realized that agents judge authors by the quality of their query that I started to hate the process. "Just read my stuff!" I cried at my computer screen. "I'm good for it!"
But no matter how we feel about them, query letters are a necessary evil. Agents get hundreds of these things a week. They can't read hundreds of manuscripts, or even sample pages, in a week and expect to get anything else done (like, I don't know, sell novels). They have no choice but to make snap judgments based on a 1-page pitch.
But more than that, I'm learning that the agents are right. They already know this, so I guess I'm speaking to the authors (besides, what agents spend their time on this blog? Pah!). If you can't write a solid, gripping, concise query letter, then chances are you can't write a good novel either.
Don't hang me yet! Hear me out!
We tend to think that writing a query and a novel are two separate skills, but they're not. They aren't the same skill, but they do overlap considerably. Sentence structure, word choice, clarity, word economy, etc. are just as important in a novel as in a query.
In learning how to write query letters, my novel writing has improved as well. I find myself being more concise, choosing words more intentionally, focusing on clarity and logic flow. I've also found that in focusing on what's important to the story for the query, it keeps me focused in the novel.
The biggest mistake writers make in queries is trying to tell everything that happens, losing focus on what's important. If can't stay focused in the query chances are you'll lose focus in the novel too, though it will be more difficult to see.
Finally, before you decide to execute me, remember that I said "chances are." It's still possible to write terrible queries and amazing novels, just as it's possible to write amazing queries and terrible novels. But by and large, the agents have a point; our query writing skills say a lot about our writing skills in general.
And in the end, if I, as an author, dismiss any aspect of writing as unimportant - if I am unwilling to learn how to write a query letter well because it "has nothing to do with writing good novels" - how good of a writer can I really be anyway?