Well then the Gricean Maxims might be of interest.

The premise describes observed phenomena; likely your questions are all answered somewhere. Folks have been trying to make language efficient since before the industrial revolution, and as a whole language has been studied from antiquity.

Sure, echos. Don't listen to echos. Nuance's impedance does not mean it is bloat. Bloat impedes without adding value.

Western? Or human?

"Unused"?! Have you ever read good Western or Eastern literature? I'm guessing you don't speak Korean or Georgian. I think you'll find Hangeul interesting :)

Philology is a fun ride. Don't hurt your tongue!