Office-Hour Habits of the North American Professor
you summed it up, no matter what rules are made they still need to be enforced. The sad part is that every time I've had a crummy professor and tried to do something about it I have gotten nowhere because noone would touch them because they had tenure. They people in charge of that particular department almost admited that the particular teacher was worthless and wasn't doing their job. It's almost like a get out of jail free card from the department. I was literally told that short of one professor killing a student there was no way they could fire him.
The ability to speak freely is definitely a good thing though, in my experience tenure still does more harm then good.