I agree that this is one of many structural issues in U.S. higher education (and more broadly). I would add, however, that "Instructional Professors" at the University of Chicago have one thing that tenure-stream faculty don't have (and legally can't have): union representation. The title "Instructional Professor" itself, along with details such as course load, renewal, promotion, annual raises, leave, and benefits, is governed by a
collective bargaining agreement between the University of Chicago and Service Employees International Union Local 73.