Well, there shouldn't have to be a Living Will. My spouse, if married, should be able to speak for me when needed. But of course, many now want the government to act as nanny, since the Tom DeLay knows me better than my spouse, I guess.
On the other hand, I think providing an advance directive/living will document helps give the survivors some guidance regarding your wishes, so it's good to provide one as a courtesy to the person who would make those decisions.
But DEFINITELY don't take a generic form and fill it out carelessly. Requirements vary by state. Here in Pennsylvania, it doesn't have to be notarized, but I have mine notarized and witnessed just because I don't want any questions... And also I hope I'll then have no problems with "do-good" meddlers trying to interfere.