Posterity. For example, I really want to get my dad's stories and family history for the kids.
I'd like to be able to have that stuff available for my brothers, or interview them and have that available for their kids, our parents, etc.
I'd like to be able to get down some audio about unit history (that won't make it into the history books) from the guys I served with overseas; their perspectives on what we did/went through all those years ago, how they've moved forward, etc.; that stuff could then be made available to everyone in our group of friends. It might spawn more memories and allow a comprehensive understanding to come together to assist certain guys who struggle with certain things. Etc.
Mainly looking at it as an archival mechanism for things which would come out in a conversation rather than asking someone to just write something down or record it on their own, since dynamics really color the end product.