I can see the value to prove fault in the case of negligent homicide. My wife and my heirs will be well taken care of.
Not only is there the initial cost of the equipment. Then there are data storage requirements. Storage is not free.
The biggest cost would be time. Time to fiddle with another piece of gear. Time to transfer/download video, time to watch or edit it. And for what? There is too little time for things that matter.
I know what I did on each day's ride. I was there. And if I'm dead, do I want my family to re-live the event? Heck no.
Seems like a huge waste to me. One man's opinion.