I used to carry a rechargeable Maglite for work when I was a teenager (long ago). I rested the main weight of the body on my shoulder, hand partially around the base of the head, with the side switch at the index, middle finger, or ring finger. One mode, so the only time you needed to press the button was for on or off. The head didn’t get that hot with the limited power of the time.
It was very comfortable and intuitive. It felt a little like carrying a short baseball bat rested on your shoulder. At the time, there wasn’t the whole “on-off… on-off… on-off” (momentary) technique taught today (that I’m aware of) so even less need for excessive button usage. The newer Streamlight Protac HL5-X works well with this technique, although it’s too short to rest the weight of the flashlight body on the shoulder.
IMO, with the smaller lights of the last 20 years, the tail switch just seems more ergonomic with the higher hold. Heat accumulation of today’s higher power flashlights is also significant around the head and not so touch friendly. Additionally, with the higher lumen flashlights of today, more lumen can be designed into the spill, which can increase the shadow casting when compared to the tight spot of the old, throwy, incandescent, Maglite style lights/reflectors.
IMO, some of the reasons for the higher “tactical” hold that don’t include defensive/offensive use scenarios might include efficiency of movement (since it is held closer to the body and related pivot), easier to find and actuate the tailswitch in the dark or with gloves, and for shining over things that are above waist height, such as a couch, railing, vehicle, bed of a truck, bushes, etc.
Generally speaking, with current flashlights I hold the flashlight low (handshake?) if I need to shine it for long periods of time, and higher (tactical and sometimes cigar) for shorter, more immediate tasks (if a tailswitch is available). With the old 4D sized Maglite, since the weight was mostly resting on your shoulder one could keep the high hold for long periods of time, even though it was a large and relatively heavy light.