his voice isn't unique or great. i don't understand how he gets these gigs
He's innocuous. Not ugly but not good looking enough to be threatening. The same thing can be said about his voice, patter and talent. He's the equivalent to musak. If you hire John Hein you may not attract anyone but you don't offend anyone. If anyone is going to watch anything Hein is on it's because the food (or the wackpacker/show staffer) is the attraction.