Stem cells are an amazing discovery! There is TREMENDOUS power in their potential to change the world and that alone makes a lot of people nervous. Who isn't a little afraid of powerful changes? First of all, the more we learn about stem cells, the more we're going to need. Preliminary research has been so promising that it's almost a sure thing. Once we figure out how to use them, the demand for stem cells will be staggering and frankly, there just won't be enough aborted fetuses, umbilical cords, and frozen embryos to go around. Then what? Scientists will have to start creating life solely for the purpose of ending it. Since I don't subscribe to the "human hypocrisy," I'm no more uncool with that idea than hatching chickens just to eat 'em.
Another thing that worries many people is the idea that if we perfect the use of stem cells, life expectancies could skyrocket and that's only a good thing on the surface. Overpopulation would become a HUGE problem and babies suddenly wouldn't be as welcome anymore, increasing the motivation for abortion which would in turn feed the stem-cell demand. Frankly, this scenario does freak me out a little because things like this could snowball in a hurry... anyone else wanna chime in?