That's just it. That is your opinion. The same could be said about many things:
Marriage. Why is the govt involved in my marriage? Why do I need to pay to get a license? What business is it of the govt who I marry, whether it be Jim or Jane?
School. Why is the govt involved in whether or not my child attends school? I'm the parent and I will decide if my child will attend school, it shouldn't be mandated by the govt.
When a person actually believes that an unborn child is a human life needing protection (not some cop-out comment that the person just wants to control a woman's body), then the discussion is valid and isn't easily dismissed. That's why the topic is so different than the other social issues dividing the left and right. Personally, I side with the left on many social issues, but I'm divided and conflicted on abortion...it's a pretty horrific act...one I sincerely try to understand.