I think that is commonly accepted that most stall/spin/crash events happen when the aircraft is near to the ground, slow and turning and when the pilot has been distracted. The commonly practiced scenario both in PPL, CPL and FI exams is the turn onto Final with 2 stages of flap on a PA28 or Cessna.
How would an AofA indicator allow for the fact that stalling AofA is less with flap than clean?