But why does ethics need to be a science?
I didn't say that ethics needs to be a science, I was simply stating that a scientific (i.e. empirical) approach to ethics is not inherently a bad thing. Things such as social darwinism and eugenics and other racist/discriminatory practices are not the unavoidable conclusion of the application of science to ethics.
I also don't believe that all of ethics can be treated in a scientific manner. I was simply trying to make the point that science is not the inherently dangerous element - human nature is. The problem is not that science leads to evil conclusions, its that the belief that science is perfectly objective allows people to hide their own biases (from themselves even). In truth, science is loaded with cultural/racial/gender biases that are the product of human nature but an empirical framework should eventually eliminate false conclusions.
What are you hoping to gain from that, if not confidence?
The goal of science is to gain an empirical understanding of the universe around us. If we are talking about confidence in the statistical sense, then sure we hope to gain confidence through science. If we're talking about confidence in the human sense, then it doesn't really help anyone and often gets in the way of progress.
I don't really know what would be gained from a scientific approach to ethics. Maybe nothing. Or maybe it would give us a better way of understanding ethics in the context of the evolutionary "baggage" that we've accumulated. It's not exactly my field of study so I can't really say what might come of it.
Lastly, I came across an interesting article on this topic as I was writing this response. I'm too new to actually post the link but it's titled "Is ethics a science?" by Massimo Pigliucci in Philosophy Now. It's not that long and worth a read if you're interested.