1. Cpt: I've seen AI fusing on the occasional DCS (some old Foxboro's that ran 10-50mA were fused) and an occasional PLC.
I never hear about the cable accidents that might take out an AI, but the 3 burned input resistors I personally have witnessed were caused by
1) the subterranean vault where the pressure transmitter was located flooded; the dirty water was conductive enough to conduct enough current to burn out the AI input located high and dry above the flooding.
2) incompetent technicians who shorted the (+) and (-) terminals at the transmitter for reasons unknown, even to them.
I'm sure there are cable faults that I don't hear about, but I'm with you, why bear the cost of 'fuse' insurance for so little prospective return? Most of the world seems to live without it. The manufacturer's cover their butts by recommending the practice.
2. MOV protection is used where lightning protection is needed or maybe EMP protection for military service. Commercial surge protectors use MOV's. I see surge protection used where experience shows it's needed - water/waste plants with long, outdoor cabling runs. Occasionally in a steel mill for outdoor cabling, but rarely inside an all metal building.