"Whether that killing (abortion) is murder is a legal question, not a moral one"?  In what universe Michael?  Murder is the unjustifiable, premeditated action of taking an innocent human life.  Abortion is, in every way, murder.  Those who don't consider it murder do so because they WISH it not to be, but you can't wish away murder.
Abortion should be criminalized for the very fact that it IS murder, and all who participate in the crime should be punished.  
Perhaps our nation will never have the moral courage to legislate the issue properly, but eventually all those who are guilty of that crime against God and the innocent will face justice.
Am I wrong, or does your argument merely boil down to, "it's killing innocent unborns, but it would be too impractical to protect them legally"?