Okay, I will play along. What is the object here of God telling this woman to abort her fetus? If God commands us to do something there is always something of a higher value at stake. What great act of faith does this woman show for saving her own life at the expense of her child's? If anything, her abortion shows that she values her own life more.
Once again, the story of Abraham is unique and the only one like this recorded in Scripture. Isaac was no ordinary child. He was the promise child. It was from him that Abraham was to be the father of a multitude. Abraham knew that and knew that God had promised him that he would be the father of many nations. Not once for a second did Abraham believe that Isaac would not be raised from the dead. He even says to his servants that he and the lad will return after offering a sacrifice. The whole purpose of this story was to foretell the plan of redemption. What great mystery of faith is being revealed to future generations by a mother aborting her fetus? None. God doesn't do anything by whim or capriciousness. There is always something of value for humanity at stake when he gives commands. So, no, abortion advances humanity in no sense. God would not command us to have one. We can't limit God, but we can understand his nature and character as revealed to us through Scripture.