These days, many couples are not married, so have different last names or decide to keep their own last names after marriage. About 30% of our foster parents have last names that don't match. This makes it difficult to find homes if you don't know both names and many reports (like the Find A Home search) lack both parents last names.
I believe the instance of couples with different last names will only grow, therefore adding 2nd parent last names to Find A Home and other reports will keep Valeo up to date with societal norms.