With all gear on a BP hunt, it is a cost benefit. I'd ask you the following:
What kind of BP hunting are you doing?
Are you ever sitting for long periods on the ground?
Would a pillow save your neck and add comfort/better sleep?
Are you carrying something that this could replace for either of the above?
I wanted something to sit on and use as a pillow. I made it for myself first, and when other hunters who hunt like I do saw it, I knew it would be a hit for enough people. Here is my cost/benefit analysis. It is so light, and for me has three consistent and valuable uses that it is worthwhile to carry.
First, as a seat, keeps my behind warm, comfy, clean and dry. I do a lot of sitting while glassing, so it gets used hours every day. Using this keeps me more comfortable and less achy. If I won't be glassing, I might consider leaving it behind.
Second, as a pillow, sleeping well and keeping kinks out of my neck is valuable. I'll be sleeping several hours, so lots of use there. When I consider how many hours I am using the bag every day, and the comfort it brings, it is totally worth it to me. If I left the bag, I would bring an alternative for sure.
The third use is as a support pillow for shooting. This is a nice benefit, not nearly as valuable as the other two. But, when I am in a field position, and could use a little extra support for a shot, I love having it along. I can and have used a jacket, pack, or something else, but its there, quick and easy, so this is a bonus use.