I've grown used to it. And honestly, playing mainly on testing, it feels weird to type in the old message box. The new one really is way handier when it comes to underlining, quoting etc. If it works as intended.
I often have that I write something in italic, then turn italics off, but that action puts my mouse back at the front of the letter and where I was typing, it's still italics.
I've learned to circumvent it by just selecting what I want to put in italics, or what I wanted to quote after I've written my letter, which is still a lot more user-friendly than the html.