This would be useful for many organizations because depending on how the Spouse is added to the database, the Preferred Address of the original Constituent is not automatically shared. It's confusing that if you add the Spouse through either the Relationships tab of the original Constituent or you make a current Constituent a Spouse, the Address is not automatically shared - but if you add using the Spouse button, the Address is automatically shared.
Agreed! I do large constituent batches to save time, but then I miss out on sharing the spouse's address. I'm not going to go back into every new constituent's record to share their address with their spouse, but I don't want to compromise the integrity of my data either!