The "rim lighting" effect, so called by the devs, gives enemies a red aura that intensifies with distance and fades away the closer to you they are. Your teammates, on the other hand, get a blue aura, but it appears to be much fainter than the red aura around enemies. The blue aura turns orange-yellow when you are in the process of buffing someone, and objectives also seem to have a yellowish-orange glow as well.
It should be called "Rockefeller Center Christmas Tree Lighting Effect", though.
Its kinda useful the only reason i find to turn it off is to be more immersible.
It totally defeats the point of giving each faction unique outfits though. If both factions would have access to exactly the same equipment it would make sense. But then again, why light up the enemy team? Only give allys an outline, so everyone who does not glow is most likely someone you'd rather want to shoot.