Actually, we assume they'll be standard contributors to society. If they go on ahead and create the next advancements on the human lifestyle, good for them. If they become petty crooks or even murders and terrorists, shame on them, they'll be dealt with. It isn't fair to get robbed of a life, a precious life, a shot to become an influence on people, fall in love, have their own families, and in turn die, looking back at the whole way there. No one has the right to deny anyone at least a chance.
There's nothing anyone can do to protect "rights" of sperm/egg cells, but once they're fertilized (or in the case of sperm, fertilizing), then the growth and life of that cell as a human being is guaranteed, apart from the tragic but natural case of miscarriage.
Religion and politics were supposed to be separate entities. The issue over whether stem cell research is morally acceptable stems from religious concerns that we are "playing god" in doing so. The ban on such research indicates that our government is still largely controlled be religion. Despite our best efforts to avert it. Religion is a poison to which science is an antidote.