I don't think it's just the syntax that's a roadblock - Clojure is not intended to be extensible in that way. For better or worse, it has batteries included and

I don't think it's just the syntax that's a roadblock - Clojure is not intended to be extensible in that way. For better or worse, it has batteries included and is highly opinionated. From that perspective, including parens in let just to enable some hypothetical extension makes no sense.