If the ransom notes were able to confirm where specific, relevant items where in the home or how they were placed (watch, etc), or what had been done to things (flood lights), then that would indicate that these things were done on purpose (duh) and with specific intent to use as confirmation of the abduction. Kind of like a serial killer and his trophies. This would then suggest that this was a well-sorted event and that the perp or perps knew in advance that there would need to be multiple special, unusual things done at, near, and/or to the home to prove that their demands were authentic. They also knew that these things would need to be done in advance if they had no intention or desire for intensive interactions, conversations, or negotiations with family or anyone else. In their eyes, perhaps, the authentication alone should be enough and there is no need to elaborate. Either pay or suffer consequences. "Believe me or not, I don't care!", in other words. This suggests complexity. And refinement. And a grudge.
Doing it this way would obviously be so that the perp(s) wouldn't put him/themselves at more risk of being tracked or located. And just like the letters being sent to media to publicize his/their brazen act, it also suggests that the ransom demand, fairly low by today's measures of wealth, could indeed be peripheral and not the primary reason for the abduction.
Just thinking a little (what is now likely considered) outside of the box.
JMO.