I'm thinking of of a exercise wide toggle, not just for each answer blank and certainly without having to post the little graphic after every answer blank. That way a student could turn it on when they got to an exercise for which this feature would be helpful but could turn it off (say) for exercises that had a lot of numerical or T/F answers.
I know several people who turn on Mathview just to have the option for instantaneous rendering of equations as the student types. For that reason, it would be very nice if that portion of Mathview (or something equivalent) were to be a toggle option for the student to select from within an exercise rather than having to go to Options.