Play a bit of Spring 1944
http://spring1944.net/ and let me know how you like directionality of turrets on tanks and artillery, as well as directionality of armour on tanks. Typically vehicles are weak at the back so easier to destroy if you can get behind them.
This is not directly directionality of LOS, but it's easy for a guy to turn their head, but slower to turn a turret. In some limited light mode (like dark maps and people using torches in a FPS) it makes sense, but I'm not sure that having cone vision would work in ZK even in a special mode.