Another answer is: I have never yet gone without at least a piece of torso sized CCF as an emergency "go to ground" back up, as well as my sit pad. I have only had to use it twice in 7 years, on the ground, but I sure was glad I had it. So since I will always have one with me anyway, it seems reasonable to me to see if it could have another use besides go to ground and sit pad. Though I mentioned full length, I am probably thinking more of torso length.
One other possibility: many people use some form of CCF added to, or built into, their packs to add somewhat of a frame. Once again, if this can actually be used to boost the HHSS, then even more multi-purpose: pack frame, sit pad, go to ground, insulation inside the hammock for if the HHSS is not enough and their is no unworn clothing available to boost it, or placed down inside the UC to avoid any of the complaints about using a pad inside the hammock. IOW, if you need all of your insulation for top warmth, or there is not enough available for placing below to reach the temps you need. Like maybe in an unexpected cold snap, or if you have messed up and got some of your insulation wet.
That's all I can think of right now. Not at all needed, but, for those who have some foam with them anyway, it just seems like it would be nice to know if it could be pushed into another service than pack or sit or fire fan. Plus, just curious.