No, modern technologies do not make us less safe as when new technologies are developed, counters to those technologies, that is safety measures, are often developed in tandem. Despite the way movies like to portray a lone mad scientist playing God, this is not how the real scietific and techonological communities work.
I believe that modern technologies do not make us less safe. In fact, I believe the opposite. I believe that they make us more safe. Technology is not threatening unless it is used in a malevolent way. Technology should be designed to be helpful, not hurtful, and that's what most technology is. Take the cell phone, for example. It keeps us safe on the road if our car breaks down or if we need to get a hold of someone in an emergency.