"Basically, is "traditional" (inasmuch as Arc establishes tradition) ssyntax prohibitively useful?"
I don't think so. Nulan completely ditched Arc's ssyntax and only uses significant whitespace, ":" and ";". Yet, despite that, it's capable of getting rid of almost all parentheses.
Oh, by the way, ":" in Nulan has a completely different meaning from ":" in Arc. I just chose it because I thought it looked nice.