The Arnold Include/Exclude functionality has many shortcomings, and it's not nearly as flexible as the old 3ds Max native Include/Exclude.
The fact that we can't include/exclude shadows separately from illumination, but only illumination and shadows together, is a major limitation.
But the fundamental issue with Arnold Include/Exclude is that it's object-centric, not light-centric. If we want a light to only shine on one object, then we have to add an Arnold Properties modifier to every *other* object in the scene. This is a workflow nightmare.
If Arnold lights had the same functionality as other lights, this would not be a problem. Lights should have the ability to include or exclude objects. Objects having the ability to include or exclude lights is not good enough for real production problems like simply trying to illuminate a character's eyes and nothing else.
So, is there any hope for a light-centric include/exclude functionality? Without it, MAXtoA is still lagging behind the lighting feature set of 3ds Max 1.0, from 1996.