It's because in a marriage you're in it together. What's good for you is usually good for your spouse and vice versa. It's information that I think is important to have.
I stress as well that this information is not made public. Only very general, broad statements are made public. But it assists us in seeing whether there is anything we need to discuss with the individuals with respect to potential conflicts, because conflicts go not only to you but to your family. If I had my way, it would be a little broader than that, which is in my other recommendations.