Why of course they would, John! At least you'd think that someone would to some degree, especially if the regiment was merely stationary. Or would they? But if a regiment were deployed and advancing under orders into the teeth of a defense, I don't believe that many of the soldiers would be paying attention to what they could see behind them, unless it was something so apparent that it couldn't be ignored. I suppose that historical rationales could be presented for each side of the discussion.
But as I said, while the suggestion would seem to fly in the face of realism, it does offers to reduce the unrealistic, 360 degree, 70-hex range we currently have with any unit. What we have now is essentially too much of a view: the "God's Eye!"
Elevation and terrain effects are currently factored into the vision capabilities. And that's good! You cannot see through forest hexes and you can't look over an intervening ridge. The line-of-sight has been pretty well constructed. But as Kennon points out, you still have eagle-like vision throughout the entire range that you currently
can see! His particular suggestions seem very sensible to me. In fact, I'd like the chance to play a game with his suggestions and mine implemented. I'd bet you the challenges and some of the uncertainties that we've all been craving would really become evident and serve to open up the realism of the games.
I suggested the three-hex, frontal arc reduction because the HPS/JTS game engine already employs the arced range capability for mounted cavalry in forests, although it is limited to only two hexes outward! (The BG games allowed a three-hex arc, three-hex distance in forests for skirmishers on foot.) It shouldn't be too difficult to adapt and expand those existing codes within the suggestion. But, of course, I am not a programmer.