I think it's the vagary of various times. All periods had pretty expensive media and some were, as one would expect, terse as hell. (Reading a book on Nagarjuna, I'm reminded that reading his Heart of the Middle Way was like trying to read a math book with nothing but theorems. And not even the proofs. 'Wait, could you go back and explain that? Or anything?') Latin prose could be very concise. Biblical literature likewise. I'm told much Chinese literature is similar (especially the classics), and I'd believe it from the translations I've read. Some periods praised clarity and simplicity of prose. Others didn't, and gave us things like Thomas Browne's Urn Burial. (We also need to remember that we read difficulty as complexity. Shakespeare is pretty easy to read... if you have a vocabulary so huge as to overcome the linguistic drift of 4 centuries and are used to his syntax. His contemporaries would not have had such problems.)