It's 1pm on a bright afternoon. You're getting sunburned and you wish you had sunglasses. Suddenly you're in a fight. You maneuver inside of a concrete building of some sort. There is no power as the local transformer was destroyed by a grenade/stray shots. It's dim in some places and pitch black in others. You hear something which may or may not be part of the enemy force. You:
a) Use flashlight to find, identify, and eliminate the enemy or avoid shooting a civilian.
b) Wait 10min inside of a dark building for an interpreter to arrive and call instructions or shout commands in broken >> insert language << that you have on cheat sheets and hope you're not telling them tomorrow's menu for a local restaurant.
c) Roll in enough grenades until everything is dead.
d) Gas the place then use your muzzle flash as your light source.
It's night time. You spot a group of insurgents making a break for a building to your left. You get off a shot using your NVS mounted scope. The rest of your squad only has helmet mounted NVS. You try to explain which building that the enemy entered. The building are all nondescript and your squad is confused. A BDRM-2 pulls up and a squadie runs over to tell them there are enemies in one of the buildings. You:
a) Use your infrared (visible except to NVS) laser mounted PEQ to highlight the building.
b) You jump on the radio and yell "follow my tracers!" (assuming you have tracers).
c) You go to each squad member and align them to the proper building.
d) You call in artillery "danger close" and pray that the cannon cockers aren't sucking down contraband vodka and that there aren't any civilian houses too close.
Let's be honest here. You don't even NEED optics or a grenade launcher. But everything you do have extra acts as a force multiplier or shores up a shortcoming. They didn't need to mount huge night vision scopes to short range M1 Carbines. But they did and that combo accounted for 30% of all Japanese casualties in the Okinawan campaign.
http://www.usrnsf.com/Rifle_History/M3%20Carbine.jpg
http://cdcfd.files.wordpress.com/2010/10/snipscm1.jpg