What would you rather have? A big guy who may not be the most nimble, or a small person who couldn't really open the door even though they say they can? Or someone who would freeze up mentally after a crash and not be able to function?
Basing decisions on unknown quantities is pretty bad. I may want the 6'8" guy who needs an extender but can also move some people and can definitely open an emergency door and throw it as far as needed.