The flashlight currently has an implementation that begs for trolling/griefing. For whatever reason, it is ridiculously bright even during the day time. This was a common complaint during the beta and it hasn't improved. There are two obvious possibilities for the functionality to improve:
The game already has HDR implemented, where the brightness of the game dynamically adjusts based on whether you're looking into/at shadows or at a bright area. If possible, the brightness of the flashlight could dynamically adjust based on this.
-If the player's eyesight has adjusted to darkness (bright of a dark room increases gradually up to a point, simulating eyes/pupils allowing more light), the flashlight should be BRIGHT, as it's amplifying all available light
-If the player's eyesight has adjusted to brightness (shadows get extremely black, simulating eyes/pupils not allowing as much light in), flashlight remains very weak
The other, less preferable way is based on the behavior of the Radio Beacon. When a Radio Beacon is placed indoors, you spawn directly on a teammate--when it's placed outdoors, you spawn in with your parachute. I don't know exactly how DICE determines this, but clearly the difference between indoors and outdoors can be differentiated.
So when using the flashlight:
-If player and enemy with flashlight are both indoors, flashlight is at full power
-If player and enemy with flashlight are both outdoors, flashlight is at little to no power (faint glow on front of the weapon)
-If player is outdoors and enemy with flashlight is indoors, flashlight is at little to no power
-If player is indoors and enemy with flashlight is outdoors, flashlight is at (or near) full power
This isn't perfect, but would at least allow for some variance in the flashlight's strength.