Well, there are a decent number of those use cases, but the one I find most compelling is storing an exact record of what another service sent me in case I need

Well, there are a decent number of those use cases, but the one I find most compelling is storing an exact record of what another service sent me in case I need it later. I pull out and store in my typed schema the relevant bits of, say, an OpenID Connect response, but I'll often store the entire response as well in case I want to add functionality in the future based on additional fields, etc. in that response and roll forward without having to have an intermediate state.