How does becoming an instructor teach 'humility'? In fact, it could work just the opposite.
Think about it: You've got a medic who clearly has a higher license level, better education and a wider scope of practice teaching those who are just begining; most will have no prior medical education and upon graduation, will have a very narrow scope of practice. This leads to a feeling of superiority, which is counterproductive to humility.
In Michgan, you have to have at least 3 years of 'field experience' before you even qualify to begin the courses to become a licensed EMT instructor. In the State of Georgia, you have to hold a current/valid State License to even be selected as an adjunct instructor. I think there's even a clause in it that says you have to be actively working in the field as well.
Instructors should be those that choose to do it, not doing it because it was forced upon them. This leads to the "I'm only here because I have to be." mentality, which doesn't bode well for teaching.
Even preceptors are in the program because they were selected and chose to do it. Not every EMT/EMT-I/Paramedic is selected to be a preceptor.
In the state of GA, (at least to the best of my knowledge), you have to hold at minimum a BS to be able to teach paramedics, and an EMT with an Associates Degree cannot be an EMT instructor.