I might be missing something, but the appeal of gradual typing to me is that I can mostly type functions, providing safe input/output boundaries, and avoid having to type every single variable (unless I have to do so for performance reasons, as I do in Common Lisp).

This approach is comfortable to me both in Erlang and in Common Lisp, I see it as a balance between safety/performances and development speed (and I'm saying that as someone using Go for all professional development and being really happy with its full static typing).