I consulted my colleagues at the OU, and they are not keen.
When we were still using Moodle 1.9, the way the correct answer was displayed to teachers caused confusion for some people about how much students could see during the attempt.
However, even if we displayed it differently to teachers, there are still some situations where we would not want the right answer visible to tutors during the attempt, so if this did get implemented, it would have to be optional, and do we really want even more options for the quiz?
I'm not saying that this should not happen, just because the OU does not like it. I am saying that if it is done, it needs to be thought through properly.