For a lot of users, WYSIWYG is good, especially if it really integrates with the web page you're trying to edit (not a non-styled IFRAME like in the traditional CMS editors).
I also usually write in Markdown, but the latest breed of editors is starting to be good enough that I may be able to swap. And as for <hr />, that is usually configurable in the editor setup.
Disclaimer: I'm an author of one the new editors, Hallo.
I don't think anybody has written that plugin yet. Could you post a ticket? I'm spending some days on Hallo and Create next week, and so could possibly write one.
I also usually write in Markdown, but the latest breed of editors is starting to be good enough that I may be able to swap. And as for <hr />, that is usually configurable in the editor setup.
Disclaimer: I'm an author of one the new editors, Hallo.