While there are certainly some arguments to be made regarding abortion being utilized when it is not needed, there are certainly cases that it is. If the mother is in danger of dying from complications, if the fetus was created due to rape, these are the two most commonly referenced. A "rape child" is never going to be treated with the love and care it needs to develop into a functional human being.
Abortion can be useful in many cases. Some abortions come in cases of life or death for the mother, and it could wind up saving the mother's life whereas giving birth could have killed her and possibly the child as well. It can also be good for mothers who have become impregnated from rape and their mental health as well as for a fetus that shows signs of being deformed or severely underdeveloped mentally.
It can save the life of a mother whose life is threatened due to complications. Many of these times, the fetus would die when the mother did, anyway.
It can help save rape victims from even more psychological scarring by keeping them from having to carry their rapists' babies. It can help save money for poor women and families who can't afford to have a child or, for whatever reason, wouldn't be able to take care of a child.
I would say that it has a lot of uses.
Pregnancy can be very harmful and dangerous for a woman. There are many cases each year in which a woman's very life is ask risk. In these cases, if the mother-to-be dies, then the unborn child will die anyway. Abortion could save the mother's life. How is that not a "useful" thing?