I also think it's a bad idea; a gift should be altruistic, without conditions attached - who are we to judge who is worthy?
Also very impractical, and would lead to the issues others have mentioned, about other ways to move up the list, determine worthiness, etc.
I don't mind the idea of opt-out, as then it might make people's wishes clearer. I am not sure about refusing to let families object, though.
I am both willing to donate and receive organs. However I also understand the inconsistency of some people saying that they feel uncomfortable about donating, but would still receive. It doesn't seem that illogical to me - if they have their own doubts about donating, then that should be respected, but presumably the person who has already donated didn't have those same doubts, or they wouldn't have done it.
I know there are some people that say you shouldn't eat meat unless you are willing to kill it yourself. I do eat meat, and yet I don't think I'd want to kill an animal myself, and I think there are other people who think the same - whether it's morals, squeamishness, or whatever variety of other reasons. Yes, perhaps somewhat hypocritical, but not uncommon, I think. However I do still eat meat, and I presume the person who is doing the killing has decided it is something that they are able to do. Clearly this is nothing like the issue of donating or receiving organs, but it does show that there are some issues where people can hold somewhat inconsistent, hypocritical, or selfish view, and not be regarded with total lack of understanding because a lot of people share that view. It's not saying it's right, but it is common - and I think that most of us have some sort of moral inconsistencies within ourselves, things that we perhaps just choose not to think too deeply about. Becoming aware, non-judgementally, of these contradictions in ourselves (and knowing that we all will have them) is one of the best ways to start considering other options and ultimately perhaps changing our minds.