Are you saying I have to turn off the lights on the soldiers in order to make aliens unable to see them? That would be problematic, as I would be unable to see the aliens and the map, even though my soldiers can see fine!
I think of the soldier light radius not as an actual light source they are carrying, but as their ability to see things that are close to them. It is for that reason that the aliens should ignore the light your soldiers are "generating" and use their night vision attributes as if your soldiers were not generating light.
Otherwise, there needs to be a way to see the battlescape without generating light on it, or else night vision armor does not work.