But what about organ donors? You are using "leftovers" in that regard, as distasteful as that me be to some. And while adult organ donors express consent, deceased minors defer to their parents' wishes. What is the difference? Forget about aborted fetuses, babies die in other ways.
What about using prisoners. Or kids on ventilators. Or orphans with birth certificates who are "left overs" because their parents can't or won't care for them properly.
Or actors on ventilators?
We do not use other human beings as means to an end. The age old medical ethics of "First, do no harm" has worked very well to protect patients and to encourage the goodness in the medical professions. Those who go against this ethic have been justly vilified: Mengele, the "doctors" who participated in the Tuskegee experiments, those who attempted genocide and eugenics by sterilization of the uninformed and unconsented.
These embryos are living human beings who could have a chance at life if implanted in a woman's uterus. Many couples are begging for the chance to adopt them.
There was a movement to decrease the embryos produced and to change the process toward freezing oocytes instead of embryos. But that pressure is lessened due to the embryonic stem cell policies of the Clinton administration, and the artificial reproduction industry has resumed its "wasteful" ways.