I started using WordPress as a CMS in 2007.. Back then, I would do things as simple as adding a couple of (admittedly bad markup) br's in the HTML view, and WordPress would magically remove them for me when it was updated.
Today, with the newest version of WordPress, I ran into a situation where WordPress is STILL editing the HTML for me.
It is my belief that, when I click on the HTML tab, I can do whatever I want.. I don't want WordPress to modify that at all. For a simple GUI experience, the Visual View is fine. If I click to HTML, I want complete control.
WordPress, Please, Please stop messing with the HTML view. Even if I put 10 br's in there, PHP code.. whatever.. I want it left alone, and I think many users would agree with me. The HTML view should have a completely "under the hood" paradigm.