You're trying to grant the reactive player multiple opportunities for extra normal unopposed rolls to move around and adjust positioning. Part of the strategy in deploying second is that you need to weigh the risks of deploying out of sight or being exposed to incoming fire. Do you deploy aggressively for overwatch and risk getting shot on the first turn? Or do you allow your opponent free reign of the board while you hide and wait for your own Active turn? Or something in between? Well if you get free Dodges any time someone pops a smoke outside of your LoF, you can freely deploy aggressively and just change your mind on your first ARO. There's no strategy involved there. This would actually severely alter the balance of Smoke ammo in and of itself, since a smoke template is infinitely high, every trooper on the board facing in the right direction would constantly be getting free Dodges.