To your newly raised point, as long as there are unwanted people, there will be murders. So, the question is, will we make those murders safe? The answer to that is usually no, we won't, except in the most horrible of societies. Abortion transfers an evil from a culpable actor (in most cases) to a 100% innocent victim (in all cases), the baby. Just legal systems abhor arbitrary victimization like that. Yes, the woman is to be considered a victim in some special cases, and regardless of whether she is 100% culpable or 1005 innocent, I still want to support her to choose life. Regardless, the baby is always 100% purely innocent, and it is an abomination to legally shift any harm from one person to a 100% innocent person. No moral system can justify that in any reasonable way. Such immorality is only supported through obfuscation, to hide the evil being done (much talk of "complexity"). The way to help the situation is to help the woman, not kill the baby.
But, again, please answer my question in the previous post about the non-special circumstance elective abortion. There is no reason to talk about special cases if we cannot talk about the mainstream cases.