The thing is, tenure is not primarily about academic freedom. Let's try and be scientific and do an experiment with one variable: what's the difference between a tenured professor and an untenured research faculty member?
"Academic tenure is a matter of debate again, most recently at First Things. To my mind, these discussions fail to get to the heart of the matter because both sides assume that the purpose of tenure is to protect academic freedom, to promote independent thinking."
An interesting, patriarchal (articulating and defending the principles of authoritarian conservatism) discussion of tenure