I'm volunteer to donate because of I accidentally die, rather that it deserve someone who would have more luck than me rather than no one.

Now in Belgium it works a bit differently. Everyone is, by default, considered as a donor.

You can then register to either refuse it or to impose it whatever your family says.

This is because the law is that the doctors must always ask the family if they are ok to give organs from diseased family member even with the "by default donor", with the registration you can say "don't ask my family and just do it".

This can be used in two situation in my opinion, the first one being family that have different conviction and may refuse despite the opinion of the diseased. The second situation (mine) being not wanting to worry grieving family with one more difficult decision to take.