Well for one thing....

I will use my SIL as an example. If she were to end up in the hospital in a coma or in surgery or whatever... her partner would not be allowed to be with her unless a "real" family member was there to allow it. but since my SIL's parents live 9 hours away that isn't always possible for them to be right there right away. But becasue my SIL and her partner aren't married her partner could not be with her until another family member were able to get there. And while they have a child... her partner gets no say in anything that happens to my SIL just because they can't get married. To me that is horrible.

At the very least grant them civil unions.