Is Brevity the Soul of Wit? Or Witless for the Sake of Brevity?

Summary: I used to write email copy, which is junk mail without the paper. (Don’t hate me for stuffing your spam folder; it’s a dirty job, but someone’s got to do it.) My creative director usually had one standard response to just about any draft I submitted: “Good, but make it shorter.” This is the axiomatic principle of writing emails. Nobody has the attention span. Nobody wants to scroll through lengthy discussion. The twittering masses are in 140-character mode. Who has time to read more than a sentence or two when you’re trying to keep up with all those Facebook updates?
It seems commonsensical.