Imo they did. They focused on adventures early on, and they've also said that you can use the classes together, but obviously if you're revamping the classes the intent is people default to the new ones but can opt into the old ones.
It just isn't that deep, no one is hiding anything, and you being confused is ok because they weren't ultra clear, but its really just weird that you keep harping on it man. Like, we know what they mean by backwards compatiable now, and no one releases an updated version of something with the intent that you'll default to the old version -- it is always a courtesy at best if the old version can still operate with the new version. That's the reality of development.