Since when did companies start assuming that B-school graduates are properties of the corporate world and that B-schools are manager churning machines?..The most important role of a B-school is to bring in new ideas that were never thought of earlier.
You would never see new ways of evaluating business performance had it not been for the new ideas brought in by B-schools across the world.And this would not have been possible if the B-school faculty happened to be from the industry.Most B-school faculty have Phds which give them total ownership of the subject in its purest form.This is what results in new ways of doing business.
If B-schools were to churn out managers who are tailor-made to execute your current way of doing business,you would never see any innovation.