Social science research shows that altering a choice from OPT IN to OPT OUT increases the number of people participating in the program. An OPT OUT for organ donation would still allow anyone with personal or religious objections to avoid becoming an organ donor. It would however, enroll many individuals into the program who don't have a strong opinion on the issue.
Given the devastating shortage life saving donor organs, an OPT OUT option would save thousands of lives at no financial cost and no impingement on personal liberty.