Where is the common sense in something like Markdown? The web is built on HTML so when i switch into code mode in the editor i fully expect to be working in HTML, not some other language. There is no need to reinvent the foundation principles of how the web works.

BTW, since day one i have avoided Tiny MCE because it modifies my HTML. I have always used CKEditor so i can use all tags in the normal way (script excluded of course).