At present, lights are clamped to an "imaginary" range of 0 to 1 that have no basis in physical reality. The GLTF spec defines a physically based light falloff and specifies real world radiometric units - which is aligned with most major game engines and 3D modeling applications.
This change should apply to all sources of lights - point lights, projectors, and the sun/moon. Sun/moon would be easiest to support first.