While knowledge of other spheres of life is valuable to us all, I am not sure I see why we should single teaching out as the one profession that we should ask to do something else before they start the job in earnest. We don't ask accountants to teach first, or lawyers to run a corner shop, so why should teachers do something different first? I dont doubt that it would be valuable experience, but I don't see the lack of it as a bigger problem than any other profession.