I don't think you can have everywhere a solid, 2-hex deep front line. and even if you could have enough artillery/inf, nothing prevents you from placing an airplane in second line anyway, so no, you cannot say a range 3 is automatically completely uselessSecondly, the first line is infantry, the second - artillery and infantry it means we can place fighters only in the third line . Conclusion LOS3 - useless.
Now, if what you're saying is that they will have a much more limited usefulness, well, we agree.
As I said before, airplanes at this strategic level WERE only marginally useful, and even that is an understatement (especially in 1914), so he reduction of their usefulness is in accordance with their historical importance
And regarding intelligence in general, even having the ability to know precisely the strength, effectiveness and entrench level of each enemy front-line unit is already way beyond realism
From a power-play point of view, I can see where it is frustrating to downgrade airplanes from their see-all satellite effectiveness to a more limited role. I can remember earlier complaints in the history of this mod about the downgrading of planes from their super-stuka offensive power to a much more toned-down effectiveness.
But even that doesn't make much sense in the end, because the enemy's planes are restricted likewise, so there is no loss in play balance.
What I see is that by adding some measure of fog of war ( let's face it, with a couple of planes on each side there is virtually no fog of war at all), an essential component of warfare, you favour a type of play based more on intuition, that rewards guessing the opponent's intentions while hiding your own. A zero-fog of war favours a much more chess-like, technical, mechanical type of play.