I haven't paid too much attention, but that hasn't been my experience. As recently as today when I type in a new number the text in the window defaults to green

I haven't paid too much attention, but that hasn't been my experience. As recently as today when I type in a new number the text in the window defaults to green (a text message), after a brief lag it turns to blue when it validates it as an iMessage account. This all happens before you enter any text in the body.