I suppose a lot of folks literally want to 'hold on.' I've had conversations with families about organ donation and, in my experience, the overwhelming majority agreed. Some however, reacted as if I was 'disrespecting' (probably not the right word but they seemed offended) the deceased. I certainly understand it's a very emotional time to make those decisions for some people. For me (and you it seems), it's a no brainer. I have no need for it. It also makes it easier that 'our' decisions are made ahead of time by listing ourselves as organ donors.
Not to digress but the living can be big donors as well....Not just blood but marrow transplant lists as well.