My impression is that high school writing assignments tend not to ask for as much volume as a student can reasonably produce without padding, but college writing assignments frequently ask for more.
If one professor gives assignments demanding at least ten pages, about topics that all invite at least that much legitimate content, other professors will feel the need to assign papers of similar length, lest they give the impression that their topics are less important, or their subject less demanding. Everyone learns to pad, and comes away with the impression that an important document should be long, because the more heavily graded their assignments are, the more page volume they demand.
I remember one of my professors assigned a twelve page paper detailing the results of the experiments our groups had spent the semester on. Mine was late, because the amount of informational content really only justified about half of that, and I was struggling to pad the paper to double length without turning it into something I would be embarrassed to hand in. When I turned the paper in to the professor, unhappy with its quality but not wanting to get more points taken off for lateness, he was astonished by the quality of my writing, and emailed me to tell me that he was confused by my claims to have struggled with the assignment, because my paper was easily the best out of the class. I found this unsurprising; he must have developed low standards for the papers his students would turn in, because his expectations for volume and content were completely out of synch.
That's funny. I had the opposite experience. In High School I just learned how to pad things out, and in college everything was actually sensible-length assignments.
The topics of rationality and existential risk reduction need their own Richard Dawkins. Their own Darwin. Their own Voltaire.
Rhetoric moves minds.
Students and masochists aside, people read only what is exciting. So: Want to make an impact? Be exciting. You must be heard before you can turn heads in the right direction.
Thus, I've decided to try harder and actually put effort into the quality of my writing instead of just cranking stuff out quickly so I can fill in inferential gaps and get to the cutting edge of the research subjects I care about.
That's why I asked LWers for their picks of best nonfiction writing on Less Wrong.
It's also why I've been reading lots of good science writing, focusing on those who manage to be exciting while covering fairly complex subjects: Dawkins, Sagan, Gleick, Zimmer, Shermer, Ramachandran, Roach, Sacks, Hawking, Greene, Hofstadter, Penrose, Wilson, Feynman, Kaku, Gould, Bryson, Pinker, Kurzban, and others.
I've also been re-reading lots of books and articles on how to write well: Keys to Great Writing, Style: Lessons in Clarity and Grace, Elements of Style, On Writing Well, The Classic Guide to Better Writing, The Book on Writing, Telling True Stories, Writing Tools, Ideas into Words, The Chicago Guide to Communicating Science, A Field Guide for Science Writers, Six Rules for Rewriting, Writing, Briefly, and Singularity Writing Advice. (Conversations with Eliezer also helped.)
I don't know if I can become the Voltaire of rationality and existential risk reduction, but it seems worth a shot. Every improvement in writing style is beneficial even if my starry goal is never met. Also, it appears I produce better writing without really trying than most people produce with trying. (If you've ever had to grade essays by honors English seniors, you'll know what I mean.) I expect to gain more by striving where I already excel than by pushing where I have little natural talent.
(I won't try to write everything well. Sometimes I should just crank things out. To be honest, I didn't spend much time optimizing this post.)
My other hope is that a few other writers decide they would like to be the Voltaire of rationality and/or existential risk reduction. May this post be useful to them. It's a list of recommendations on writing style pulled from many sources, in no particular order.
And, just one piece of process advice. Do not apply any of these rules while drafting. Instead, write down whatever horrible shit comes out of you and do it quickly. Then revise, revise, revise.
Now: What are your favorite pieces of writing advice?