Many people do, but it is not needed...and it not really even metaphysical. The unborn human is still a human...a 100% unique human who simply has not yet been born.
Being born is where the legal line has been placed to determine personhood - which is a requirement for any rights at all. Much of the debate is simply a discussion about if that is the correct place for the line to be at, or if it should be earlier.
Both sides usually end up falling into the emotional appeals trap, which clouds the issue and prevents any meaningful discussion.
IMO, abortion should not be legal except in the case where the mother will die and that resulting death will also kill the child. I believe all attempts to save both the mother and child should be made, even if we expect the child to not live after extraction from the mother.
Abortion is the purposeful killing of the unborn human...if the human is removed knowing it will almost certainly die, but the intent is to try and prevent the human's death, then it is fully acceptable and is then no different than any other risky operation.