This debate sounds to me like the death panels arguments you guys have over socialised healthcare.
I live in an European country and they don't happen. Neither would Evil doctors cutting you into pieces for profit. We aren't China.
I think priority should go to the one with the most live left in them. So kids or young people in general.
It shouldn't go to people who will waste them by their own life choice, so if you are an alcoholic or a heavy smoker, you've made your bed now sleep in it.
I think it is a good thing that my country has a default opt-in position, if that's a problem for you to give your organs no problem, just opt out.
You shouldn't get discriminated against for your beliefs.
With a default opt-in, I think it is just one less thing to think about for the family during hard times and the death of a loved one.
You do a good thing by default and possibly save multiples lives. Not a lot of people have the strength of will to go trhough with it even when they want to
In better news, with the upcoming technology, I look foward to a world where we don't need to have this conversation.
Great progress is being made toward artificial organs and there is a good chance they'll work during my lifetime.