Doesn't bother me if someone wants to take bits of me, but I know a few people who have no intention of being a donor, and that is their right.
Saying they don't deserve to have anything (if they need it,) is bollocks. I trust every single person saying this has donated blood, bone marrow, eggs, blood platelets, a kidney, part of your liver, part of your lung, part of your pancreas, some of your hair, and also shit loads of stuff to food banks and charity shops and charities, and lots of time to volunteering too. If you haven't, I hope you never expect fuck-all for free! 
Daft.
Some people have very personal and private reasons for not wanting to be an organ donor, and religious reasons too, and they don't deserve to be berated for it. So what if they want or need something some time? Plenty of people give more than they take in life, or take things that they don't give to. Including the pearl clutchers on this thread.
And saying 'I bet you would want your CHILDREN to have 'donated organs' if they needed them!' is a nasty thing to say, and a low blow.