The reason people don't like to read the average design doc is because the average software engineer doesn't have enough writing skills to express the concept clearly and concisely without editing. The design doc becomes a mumble jumble of raw notes that nobody really understands except the author. And then people dread reading this kind of raw notes.
However, if someone tells that design doc writer that this is something like a term paper at school that is being graded, they can actually improve their writing by quite a bit by doing some editing. So the symptom is really the same as prototyping: people write draft-quality design docs and magically hope it to be a good quality piece of writing suitable for a wider audience. What they need is a few rounds of editing, just like when they write prototype code they need a few rounds of refactoring.
However, if someone tells that design doc writer that this is something like a term paper at school that is being graded, they can actually improve their writing by quite a bit by doing some editing. So the symptom is really the same as prototyping: people write draft-quality design docs and magically hope it to be a good quality piece of writing suitable for a wider audience. What they need is a few rounds of editing, just like when they write prototype code they need a few rounds of refactoring.