Python has logic programming (Pyke). But, in principle, yes: you can't add new syntax to non-homoiconic languages. You can use macros (even C has macros), but they are more limited in a nonhomoiconic language.
In my experience, though, metaprogramming is of limited use as anything other than syntactic sugar. And it often leads to very confusing code.
Other language features are far more fundamental and important: libraries, good integration with the shell, coherent error messages (!), readability, tooling, deployment, etc. As a language Clojure is beautiful, but as an ecosystem it has very far to go.
