I can't understand why anyone would refuse to donate organs, other than a specific religious belief that forbids it. What use does anyone have for them after they're dead?
OTOH, I understand that doctors are sometimes (often?) hesitant to bring the topic up with the family of a dying or deceased person.
FWIW, I signed mine and have made it clear to my family that I want my organs donated. They may not be in the best of shape given the abuse my body has taken, but people who need organs aren't usually too picky.
And who knows? In this crazy world, I suppose anything is possible.