That's correct, they don't light very far, but they do diffuse a lot of light over a wide angle, which is how people can see you coming towards them, but they aren't intended to increase your viewing distance. Without the fog in the way, they become blinding, which is why you don't use them in clear conditions.
They are adjustable, unscrew the two bolts at the top of the unit and pull it out and there's a wheel on the back to adjust it, but they've already been set up and no adjustment is required.