But he does holds a point, muzzle flashes do not occur that much in real life, it mostly depends on what kind of weapon, kind of ammo, the condition of the ammo. The muzzle flash appears because of the combustion of gunpowder that remains in the barrel, when it fires the gas in the barrel mixes together with air giving the flash... This does not always happens, when you fire a shot that gives a flash, the barrel is clean, the next shot will give a clean shot...
But RO has muscle flashes on every shot or it will be impossible to spot someone when a shot does not give a muscle flash!
But Bad Company 2 has a very good muzzle flash system, some shots give flashes, some do not:
YouTube - Battlefield Bad Company 2: First Mission 1/2