First, define full time professor. In my mind, this is someone who focuses on teaching first, research last. Undergrads outweigh grad students, and going off on sabbaticals is intended to improve teaching, not get new publications. that stated up front, my bent is clear.
If by this you are advocating separating teaching faculty from research faculty, I might be with you. If you intend for research to be last for ALL faculty, you have lost me big time. Research is not focused on grad students, but on the advancement of knowledge. In medicine, the sciences, engineering, and many social science fields, this would be the death knell of our advancement as a society and an economy. To be trite, a cure for cancer is not accomplished by putting research last for all full-time faculty.