Call me ignorant but was there some reason they couldn't visit before ? Why does O have to once again micro-manage life from the oval office ?
I think the visitation thing is a non-issue. AFAIK, the only time visits are restricted to blood/marriage relatives is when a patient is in the ICU or something. But I've never heard of a verification requirement. In fact, when a friend of my sister's had a lung transplant and was in ICU for months, an old friend of hers from high school just told the hospital he was her brother (her husband was known to them! She was an only child, but I don't know if that would have been in her medical record). No one made him prove it. No one made my sisters and me prove we were relatives when we visited my father in the ICU.
The medical decision thing is different. Probably anyone who doesn't have a spouse (and even then assuming divorce isn't imminent!) should probably designate. I've seen cases reported where family members went to court over disagreement about care (remember Terri Schiavo!).