Yes, sure, "expressability" is something that is hard to quantify.
Otoh, there should br some connection between grammar complexity and written culture. It is my hypothesis but, say, culture with a rich novel writing tradition leads to a complication of the language grammar. A 3 page long sentence, anyone? One can see how Middle Egyptian literature made the underlying language more complex.
Otoh, there should br some connection between grammar complexity and written culture. It is my hypothesis but, say, culture with a rich novel writing tradition leads to a complication of the language grammar. A 3 page long sentence, anyone? One can see how Middle Egyptian literature made the underlying language more complex.