There are times when individuals have roles in the course that require "Teacher" functionality (setting up Gradebook or grading, for example). Our instructional designers run into this concern - we need access to set things up and troubleshoot, but we do not interact directly with students with these individuals being visible and given the "Teacher" role. In ANGEL, we were able to "hide" people if they worked on the course behind the scenes, but did not directly interact with students. This way, only "visible" members of the roster are visible to students.
It would be beneficial to all instructional team members and students if that functionality could be added.