Principals as professional developers

What would happen if every principal saw their role as both an instructional leader and a professional developer? At present, if one would ask the "average" principal about his or her role in the school, I am sure the answer would sound something that includes the words leader, manager, instruction, students, community involvement, etc. The phrase "professional developer" would probably not emerge. When principals see their role inclusive of providing professional development for his or her staff, then a change in the school's culture occurs. Conversations with teachers focus on instruction in a deeper manner. All stakeholders within 
the building begin speaking the same instructional manner. Your thoughts?