Student teaching is probably one of the most important aspects of an educational program. In fact I would rank it second, after mastery of subject matter, but above methodologies. What differentiates it from these other areas is the experience of interacting with the dynamics of the classroom under the guidance of an experienced and caring teacher.
Some of the traditional non-academic lessons to be learned from student teaching involve,
1) classroom management 2) student discipline 3) effective speaking/communication 4) students' family/parents problems 5) departmental politics 6) culture of the school and community
Possibly many education programs thumb their noses at some (or most ?) of these, but from my own experience, I know that industry and government does not (In these non-academic areas, effective communication is sine qua non for survival).
Beyond the classroom, I'd believe that student teaching should naturally evolve into some form collaboration with master teachers. I don't know how many (if any ?) schools support this approach, but I think we'd all be more effective teachers if we did.