Need? no. Could it be improved on? I am certain it could (and Rust looks like an interesting way to do so), but that improvement would probably not be via a Turing-equivalent macro language that could, to an arbitrary degree, subvert the semantics of the language in which the programs are actually written. The trend has been to move away from macro-processing code, rather than towards strengthening the macro processor's power.
One might argue that C++'s template sub/co-language is a counter-example, but, putting aside the question of whether it is actually progress (on balance, I think it is), it has a syntax which discourages its use in a completely arbitrary way.
Sorry, I was being cryptic, my fault. I was generalizing your claim about macro languages to other languages.
I mean, doesn't your original argument imply that there is no need for a systems language besides C empirically on the basis of the number of things that get done without one, and more formally on the basis of Turing equivalence?
One might argue that C++'s template sub/co-language is a counter-example, but, putting aside the question of whether it is actually progress (on balance, I think it is), it has a syntax which discourages its use in a completely arbitrary way.