I have noticed this Twitter feature, and I question its effectiveness. Twitter changes its interface all the time. I thought the quote tweet screen was just another instance of that kind of change, which I have become resigned to.
The change has not slowed me down or made me thoughtful. It might have done if Twitter had put some sort of announcement up explaining what it was doing..
All the change really trained me to do was ignore the quote tweet screen.
I have completely forgotten the change has occurred, having internalized the process for retweeting. My fingers do it automatically now just like they used to.