Editors often see dense prose as an exercise in vanity on the part of the writer. Having been both, I know that this isn’t always the case. It may not be that the writer is simply in love with “the sound of their own voice,” as it were. Instead, it may be that the writer is in love with the thought that they are attempting to convey. Unwilling to lose any of the complexity, depth, or nuance that they are so busy enjoying, the writer polishes the prose meticulously into a state so dense that it is nearly unapproachable. Given the topography of any truly lovely thought, how could it be otherwise?
The editor’s regrettable but necessary job is to be the totalitarian petty bureaucrat—to water the prose down, to lose most of the nuance and nearly all of the complexity, so that there is no chance (and therefore, ultimately no need) for the reader to attempt to digest the entire landscape of the idea as the writer visualized it. In the end the reader is left with a merely adequate nugget—the largest body of information he or she was really prepared to approach in the first place, if the editor’s judgment is sound.