It is what the majority then and there happen to like, and immorality is what they dislike.” ~Alfred Whitehead
The only argument against Stem Cell research, is that it's "unethical." But what exactly is ethics; other than a survival code that has been exaggerated and used to give many a false sense of self-righteousness? And what exactly are we preventing here? The potential life of a human being? To what significance does that carry? Sure it could possibly be the next person to save or destroy our state, country, or planet. It could be some genius that uses its intelligence to do "good" or "evil." But chances are, it'll just be another being that exists for the sole purpose of breathing in and out and wondering around in a absent-minded state as it searches for its "reason." As it grows older, it'll realize there is no such thing and it will make one up instead of accepting the truth. It'll continue its meaningless life by using whatever outside drama it may have in order to keep its life interesting and seemingly useful. Now with its "point" in life figured out and its mind being distracted by other peoples' business, it will contently march in the line that everyone else so obediently and blindly follows, until it dies.
Personally, I think we're doing this potential human a favor. Why allow one a life that doesn't even know of the horrors and beauties of this world, when you can use it to possibly keep alive someone who understands and can make the decision of whether or not this life is worth living? It may as well be useful to those of us who are alive, than become another potential consuming being.
Simply put, I believe that ethics is not a valid argument for any subject and it is unwise to let an embryo go to waste.