Editing the genes of human embryos for human being is a complicated work that cost a fortune even though with modern science revolutions, as living life on earth we should never cross this line because our body help us to prevent naturally certain diseases, editing the genes will be equally to majority of majority of people which means only wealthy people will get better health and let other poorly suffering. In addition maybe this editing might help prevent diseases but living in the same environment same planet same air , water will be still have a chance spreading the contamination, as a consequence this editing will lead to invulnerability and wasted.
As you want to cross this line what happens if this editing embryos face with error and instead of preventing disease it gives a rare mysterious disease?