I've run into several instances where I need to modify the final result of lighting operations, and it seems like it would be a more flexible architecture to, instead of having a handful of special, magical "master" nodes in which all the lighting takes place, have a final output color node that serves as the terminus of the shader. This would mean the lighting nodes such as PBR, Unlit, etc, would have an output that could either feed into this required terminus, or instead could feed into additional logic that processes their output before outputting the final color result. Unless I am missing something, as it is, there is no way to add effects onto the result of the lighting. Your custom logic can only process/produce one or more *input* values to PBR, Unlit, etc, but not the output. This is very limiting. EDIT: A good example of a common use case of needing to modify the final lighting output is custom fog effects.