Please do write it! What I love about vim is that it is (to me anyway) a DSL for editing a document. The language has verbs "delete, copy, change" and nouns (paragraph, document, line) etc. that you can learn and combine. So once you understand how the language works, you can do a huge amount with it.

I'd love to see a similar thing for emacs, outlining how it is supposed to be used and explored and fits together.